created demand mode for creating strips

added an image button to switch between timer mode and demand mode.
in demand mode, long-pressing capture button will enable capturing and
the app creates the composite picture when user takes four pictures in
a row.
added a new ImageButton for changing the mode
added longPress event for the capture button to start and stop sessions
in demand mode.
refactored pre-capture commands into a method
renamed revertViews method to cancelCapturing
updated about me
updated versionCode: 4
Merge branch 'development'