show review notifications for all changes

- instead only of changes from currently open projects
- fix warn notifications that no Git repositories are available because of loading order (review notification gets loaded early in startup project loading process))
minor cleanups
add support for anonymous users

- if no username / password is entered, requests are done without user information
- allows at least read-only operations with Google Gerrit instances

Related to #44
set connection timeout to 30s

- since we do HTTP operations asynchronously now, it may be higher
port from commons-httpclient v3 to apache.httpcomponents v4

- fixes at least some ssl issues (certificates with broken chain)

Resolves #26
Related to #43
Merge remote-tracking branch 'origin/master' into intellij13