Implement tests

[Henni]

83 fixed phpunit. Now we should also use it to test the php backend.

Tests should be written for:

Controllers:

• [ ] ApiKeyController
• [ ] FavoriteController
• [ ] LocationController
• [ ] PageController

  Mappers:

• [ ] ApiKeyMapper
• [ ] CacheManager
• [ ] DeviceMapper
• [ ] FavoriteMapper
• [ ] LocationMapper

@v1r0x As you implemented a lot of this, maybe you can also start creating tests.

This should either be part of Milestone 0.1 or 0.2

[v1r0x]

Have a look at how tests are done in php, but as soon as I know it, I'll start testing. I'd like to release 0.1 asap, but I think we should at least cover some basic tests.