Refactoring: removed WatchService
PullRequest: save Attachement on edit
refactoring: move duplicated code for getting branches from Receivecommand
pushed-branch: when a branch is deleted, delete related pushed branch.
pushed-branch: when a pull-request is reopened, delete related pushed branch.
DOCS: added a doc for validations
pullrequest: remove redundant synchronized block
pullrequest: use a lock object per a project
Markdown:remove underline for h1 heading and change underline style to solid for h2 heading
Watch: fixed broken tests
messages: Sort in ascending order.
Merge branch `bugfix/pushed-branch` of kjkmadness/yobi

from pull request 532
Issue: update timeline automatically without flinch
IssuePreviewer works on document without reattach
PullRequest: fix pullrequest findNewCommits bug
JodaDateUtil: add date string method
Merge branch `fix/sort-messages` of npcode/yobi

from pull request 546
Merge branch `improve/pullrequest` of alecsiel/yobi

from pull request 544
Merge branch `refactoring/watch` of whiteship/yobi

from pull request 523
Merge branch `bugfix-pullrequestcommit` of alecsiel/yobi

from pull request 548