Add ability to configure core, fixes #17

app/src/main/AndroidManifest.xml

...ain/java/de/kuschku/quasseldroid/dagger/ActivityModule.kt

...main/java/de/kuschku/quasseldroid/ui/chat/ChatActivity.kt

...uschku/quasseldroid/ui/setup/ServiceBoundSetupActivity.kt

...in/java/de/kuschku/quasseldroid/ui/setup/SetupActivity.kt

...in/java/de/kuschku/quasseldroid/ui/setup/SlideFragment.kt

...ava/de/kuschku/quasseldroid/ui/setup/SlidePagerAdapter.kt

...roid/ui/setup/core/CoreAuthenticatorBackendChooseSlide.kt

...droid/ui/setup/core/CoreAuthenticatorBackendSetupSlide.kt

.../kuschku/quasseldroid/ui/setup/core/CoreBackendAdapter.kt

...chku/quasseldroid/ui/setup/core/CoreBackendChooseSlide.kt

...schku/quasseldroid/ui/setup/core/CoreBackendSetupSlide.kt

...e/kuschku/quasseldroid/ui/setup/core/CoreSetupActivity.kt

...u/quasseldroid/ui/setup/core/CoreSetupFragmentProvider.kt

...asseldroid/ui/setup/core/CoreStorageBackendChooseSlide.kt

...uasseldroid/ui/setup/core/CoreStorageBackendSetupSlide.kt

...e/kuschku/quasseldroid/ui/setup/core/QuasselSetupEntry.kt

app/src/main/res/layout/setup_core_backend_configure.xml

app/src/main/res/layout/widget_core_backend.xml

app/src/main/res/layout/widget_quassel_setup_entry.xml