New branch for challenge feature
Created model, activity and layout file for challenge.
Added a test button in activity abstract challenge.xml
Added Challenge button to layout and corresponding string
Fixed merge conflict with strings
Experimenting with opening challenge activity at button click
Adding button and fixing layout

@ activity_abstract_challenge
Coverting TextView -> LinearLayout, XML
Better grouping of fields @ challenge.xml
Changed name activity_abstract_challenge.xml

to activity_alarm_challenge.
Empty class: ChallengeActivity
Setting correct contentview in AlarmActivity
Added XML: challenge and prechallenge.
Challenge button finally implemented
ChallengeActivity deleted
Working on a simple math challenge, currently buggy
Fixed merge conflict with deleted file
A package for different challenges
Fixed math challenge activity view, working on handling input
Commit to share progress with exception