Issue-833. NullabilityTest.java fixed and unignored.
Merge branch 'master' of github.com:aistomin/jcabi-github into Issue-833
Issue-833. Some fixes after update from 'master'.
Issue-833. Puzzle removed.
Merge branch 'master' of github.com:aistomin/jcabi-github into Issue-833

Conflicts:
	src/main/java/com/jcabi/github/mock/MkUsers.java
	src/main/java/com/jcabi/github/wire/CarefulWire.java
Issue-833. Some fixes in new added methods came with update.
Issue 829: initial commit
Merge remote branch 'fork/Issue-833'
Merge branch 'master' of https://github.com/jcabi/jcabi-github into 789
Issue 789: code review changes