Merge pull request #12 from countschokula/master

Working NotificationService, with NotificationFragment and Algorithm TestCase
first super simple invitation functionality-- btw back stack example in InvitationButtonListener
Merge branch 'master' of https://github.com/ese-unibe-ch/ese2013-team6
made days in weeklymenuplan ordered by using TreeMap
working on restructuring
overall improvements / fixes
FIXED ANOTHER STUPID ANDROID BUG....
first version of login
Merge pull request #13 from dvicini/master

Some overall work to get users integrated
added friends
Merge pull request #14 from dvicini/master

added friends
ActionBarTabs in InvitationBase class
ActionBarTabs, InvitationBase class plus subshells
Merge branch 'master' of https://github.com/ese-unibe-ch/ese2013-team6
invitations (partly)
Merge pull request #15 from dvicini/master

invitations (partly)
More GUI shell, need to commit for pulling
Merge branch 'master' of https://github.com/ese-unibe-ch/ese2013-team6

Conflicts:
	src/MensaUniBe/res/values/strings.xml
now user can download invitations he received (Inbox) and invitations he sent (outbox)
Merge pull request #16 from dvicini/master

now user can download invitations he received (Inbox) and invitations he...