Fetch pull request from source repository after updating repository.
Merge branch 'pullreq-update-in-push' of https://github.com/odz/gitbucket into odz-pullreq-update-in-push

Conflicts:
	src/main/scala/app/PullRequestsController.scala
(refs #211)README.md detection is case insensitive and it also detect README.markdown as same as Github.
(refs #204)Add some way to configure data directory.

1) system property of JVM (e.g. -Dgitbucket.home=PATH_TO_DATADIR)
2) java -jar gitbucket.war --data=PATH_TO_DATADIR
3) Add context parameter "gitbucket.home" to web.xml
(refs #204)Change the option name from --data to --gitbucket.home