Add readme files for blacklisted plugins/backends

Following the discussion in getting-things-gnome#222

GTG/backends/unmaintained/README.txt

@@ -0,0 +1,30 @@
+These backends are unmaintained. Currently they don't work and we are looking
+for new maintainers. They might eventually be deleted if no one steps up to fix
+and support them.
+
+If you are interested in taking over one of these, let us know in the bug
+tracker!
+
+--- 
+
+Evolution synchronization service has dependencies:
+  * python3-evolution
+  * python3-dateutil
+
+Because of a bug in PyGTK (see https://bugs.launchpad.net/gtg/+bug/936183),
+the synchronization service freezes GTG and the synchronization service can't be used.
+
+MantisBT synchronization service has a dependency:
+  * python3-suds
+
+Launchpad synchronization service has a dependency:
+  * python3-launchpadlib
+
+Gnote and Tomboy synchronization services has no external dependency.
+
+Identica and Twitter synchronization services are shipped with the local
+version of Tweety library.
+
+Remember the Milk synchronization service is shipped with a library for RTM api. It has an external dependency:
+  * python3-dateutil
+

GTG/plugins/unmaintained/README.txt

@@ -0,0 +1,21 @@
+These plugins are unmaintained. Currently they don't work currently and we are
+looking for new maintainers. They might eventually be deleted if no one steps
+up to fix and support them.
+
+If you are interested in taking over one of these, let us know in the bug
+tracker!
+
+--- 
+
+"Bugzilla" plugin dependencies:
+  * python3-bugz
+
+"Hamster Time Tracker Integration" plugin needs a running instance of Hamster.
+
+"Notification area" plugin has only an optional dependence for systems
+which supports indicators:
+  * python3-appindicator
+
+"Tomboy/Gnote" plugin needs a running instance of Tomboy or Gnote.
+  * python3-dbus
+

README.md

@@ -51,9 +51,6 @@ external services) which needs additional packages to work correctly.
 
 ### DEPENDENCIES FOR PLUGINS
 
-"Bugzilla" plugin dependencies:
-  * python3-bugz
-
 "Export and print" plugin dependencies:
   * python3-cheetah
   * pdflatex
@@ -64,45 +61,6 @@ Installable on Debian-based system via
 
     $ sudo apt-get install python3-cheetah pdftk pdfjam texlive-latex-base
 
-"Hamster Time Tracker Integration" plugin needs a running instance of Hamster.
-
-"Notification area" plugin has only an optional dependence for systems
-which supports indicators:
-  * python3-appindicator
-
-"Send task via email" plugin does not have any external dependencies.
-
-"Closed tasks remover" plugin does not have any external dependencies.
-
-"Tomboy/Gnote" plugin needs a running instance of Tomboy or Gnote.
-  * python3-dbus
-
-"Urgency Color" plugin does not have any external dependencies.
-
-### DEPENDENCIES FOR SYNCHRONIZATION SERVICES
-
-Evolution synchronization service has dependencies:
-  * python3-evolution
-  * python3-dateutil
-
-Because of a bug in PyGTK (see https://bugs.launchpad.net/gtg/+bug/936183),
-the synchronization service freezes GTG and the synchronization service can't be used.
-
-MantisBT synchronization service has a dependency:
-  * python3-suds
-
-Launchpad synchronization service has a dependency:
-  * python3-launchpadlib
-
-Gnote and Tomboy synchronization services has no external dependency.
-
-Identica and Twitter synchronization services are shipped with the local
-version of Tweety library.
-
-Remember the Milk synchronization service is shipped with a library for RTM api. It has an external dependency:
-  * python3-dateutil
-
-Remember the Milk is not maintained for a long time and might be potentially harmful.
 
 ### HOW TO USE GTG?