#20 Added remove() method to Gists

Added remove(String name) method to Gists to delete a gist by name, plus
unit and integration testing.
#20 fixed code style

fixed code style.
#20 fixes
from master
fixed merge conflicts
#20 fixes
Merge branch 'master' into 20
contents method added to Repo
Contents interface and Rt class added to API
Content interface added. RtContent and RtContentTest annotated with todo
puzzles
Content interface added. RtContent and RtContentTest annotated with todo
puzzles
Puzzle updated to reflect mock implementation needs.
formated MkRepo class.
Mocks for Contents and Content added.
Todo tests and integrations tests added to RtContents class
Code style issues fix.
Merge branch 'master' into 20
#20 Solved RtGistsITCase
Removed checkstyle check for ClassFanOutComplexity in class RtRepo
Merge branch 'master' of https://github.com/jcabi/jcabi-github into 118