Use SharedPreferences.Editor.apply() instead of commit().

Suggested by android-lint.
QuestionFragment.ClassificationInProgress: Add the CREATOR object.

Noticed by android-lint. Strangely, it doesn't seem to be used by the current
code, which recreates (or maybe just reuses) the ClassificationInProgress
fine already.
Remove incorrect/obsolete layout parameters.

Suggested by android-lint.
Correct layout params of ScrollViews.

Suggested by android-lint.
Remove unused resources and layouts.

Suggested by android-lint.
Layouts: Use *Start/End instead of *Left/Right.

Suggested by android-lint.
Minor code style fixes.

Suggested by android-lint.
Remove unnecessary imports.

Suggested by android-lint.
Use some more Java 7 syntax.

Suggested by android-lint.
Add a TODO comment.
LoginActivity: Remove some dead code.
*ResponseHandler: Remove unused ContentProvider field.
HttpUtils: Remove unused callback.
Help dialog: Avoid a nested ScrollView.

Suggested by android-lint.
build.gradle: Use specific gradle version.

Suggested by android-lint.
Layouts: Extract some text to (translatable) string values.