change english font, modify label editor UI (#170)

- set english font to DroidSans, Tahoma
- modify label editor with issueform UI
modify pull requests list to use common css

Conflicts:
	app/assets/stylesheets/less/_common.less
	app/views/git/list.scala.html
change layout of issue list

- label manager added to issue list
- make issue list as row-fluid
fix styles

- global watch button style
- code diff font alternatives, position of commit log
Merge branch 'master' of https://github.com/nforge/hive into label-130704
remove wrong usage of .nbtn-group
Merge pull request #312 from laziel/label-130708

change english font, modify label editor UI (#170)