minor #7389 revise deprecated bowerphp link (behram)

This PR was submitted for the 3.2 branch but it was merged into the 2.7 branch instead (closes #7389).

Discussion
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revise deprecated bowerphp link

http://bowerphp.org/ uri is not working right now. So transform link to github repository uri.

Commits
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e359770 revise deprecated bowerphp link

Author: xabbuh

frontend/bower.rst

@@ -143,7 +143,7 @@ enough to ensure only bringing in compatible versions.
 
 .. _Bower: http://bower.io
 .. _`Node.js`: https://nodejs.org
-.. _BowerPHP: http://bowerphp.org/
+.. _BowerPHP: https://github.com/Bee-Lab/bowerphp
 .. _`Bower documentation`: http://bower.io/
 .. _Bootstrap: http://getbootstrap.com/
 .. _Gulp: http://gulpjs.com/