Employ kotnetcli test server in travis CI script

[jovanbulck]

Travis continuous integration script should use a kotnetcli test server to automatically test kotnetcli functionality on each commit. We can proceed as follows:

1. Running a kotnetcli test server (on localhost or permanently available remote test server) with a known dummy database.
2. Writing a simple shell script that takes advantage of the known dummy database to invoke kotnetcli with all possible outcomes, looping over all possible communicators. The shell script should verify kotnetcli's return code accordingly (see issue All ideas for numbering the error codes are welcome here. #55 ).
   • non-existing user
   • correct user, wrong password
   • correct user, invalid institution
   • correct user, max ip
   • kotnetcli server offline (in 'Kotnetverbinding testen' step)
3. We can furthermore extend our test server to yield the following two cases (e.g. when trying to log in with a specific dummy username or institution reserved for that purpose):
   • kotnetcli server internal error
   • kotnetcli server unkown rc code
   • kotnetcli server connection timeout (in 'Gegevens opsturen' or 'Gegevens verwerken' steps)

[GijsTimmers]

Agreed, very nice idea, go ahead as you please.