fixes #1252

* Sign out before logged in.
* Change activity author name "redMine Admin" -> "Redmine Admin"
refs #1188 refactoring. change element name and id based on rails term.
refs #1188 refactoring. HudsonSetting#url, url_for_plugin can add slash by himself.
refs #1188 refactoring. controller can use HudsonSetting#jobs instead of HudsonSetting#job_filter
refs #1188 make clearly that auth password is filled.
fixes #1255 remove look and feel.
refs #1188 truncate message
fixes #1257 rename Gemfile to avoid conflict.
refs #1257 add Gemfile to .hgignore
fixes #1258
fix after 1.502 SECURITY-13 patch commit 0271fdb8a21ea6747a8b9a381274b45e13ca944b
if you have many jobs, this fix could make api requests much faster
refs #1264 fixed invalid request. (need 'depth=1')
fixes #1279 direct access to @available_filters member is required to support redmine.2.2 or earlier.
refs #1256 update version.
refs #1256 update readme.
Added tag 2.1.2 for changeset 4786bf848c3e