RtRepoTest fetchKeys test method added.
Repo and RtRepo enhanced with keys method
DeployKey added to API
remove unused import from RtDeployKeysTest
MkDeployKeys implemented with Test Case
Code Style fixes for DeployKeys feature
Merge branch '119'
Merge branch 'master' of https://github.com/jcabi/jcabi-github into 119

Conflicts:
	src/main/java/com/jcabi/github/Repo.java
	src/main/java/com/jcabi/github/RtRepo.java
Repo.java resolved checkstyle issue.
Merge pull request #145 from andrescandal/119

#145: pull request 119