Release 0.9.0

The 0.9.0 release is a large change from 0.8.0 in the way Glide works. A couple highlights include:

Glide now looks, by default, at the import tree in use rather than the complete possible tree of imports. There is a switch to use the old method.
A large refactoring of the code that makes it easier to understand and contribute to.

• Fixed #262: Using correct query string merging for go-get queries (thanks gdm85).
• Fixed #251: Fixed warning message (thanks james-lawrence).
• Adding support for IBM JazzHub.
• Fixes #250: When unable to retrieve or set version on a dependency now erroring
  and exiting with non-0 exit code.
• Issue #218: Added glide rm command.
• Fixed #215: Under some error conditions the package resolver could get into
  an infinite loop.
• Issue #234: Adding more options to the glide.yaml file including license,
  owners, homepage, etc. See the docs for more detail.
• Issue #237: Added Read The Docs support and initial docs. http://glide.readthedocs.org
• Issue #248: Uses go env to get value of GO15VENDOREXPERIMENT due to 1.6 enabling
  by default.
• Issue #240: Glide only scans used imports rather than all paths in the tree.
  The previous behavior is available via a flag.
• Fixed #235: Glide on windows writing incorrect slashes to files.
• Fixed #227: Fixed ensure when multiple gopaths.
• Refactored Glide
  • Many features broken out into packages. All but action/ can be
    used as libraries.
  • Cookoo is not used anymore
  • The action/ package replaces cmd/