Tab bar created

Created a tab bar with two tabs. One for incoming questions and one for
reviewing answers.
Summaries and comments add to all methods

Summaries and comments add to all methods. A few changes in the naming
of some variables.
Summary fix
Merge pull request #1 from koekoek/master

Tab bar created
Commit Remco

Add screens, created mockup data, create to parse the data through
screens, to do: add review, load reviews in screen and make different
between user and reviewer.