Fixed the avatar problem when gitlab is deployed at the relative url.

The commit fixes the following problems:
The avatar is broken when the gitlab is deployed at the relative url.
(Gitlab-7.0-stable)
The avatars in the network diagrams are displayed incorrectly. (Before
Gitlab-7.0-stable)
Eliminate parentheses for method calls with no arguments

Eliminate parentheses for method calls with no arguments.
No need to use the to_s function

No need to use the to_s function.
Merge remote-tracking branch 'origin/master'