Remove content that can be now be found on bower.io

Now that [bower.io](http://bower.io) got an upgrade, we can remove a lot of duplicated content. Here's what I removed: 

+ bower.json
+ custom install directory
+ bower search
+ using bower cache
+ .bowerrc
+ continuous integration server
+ interactive configuration
+ Defining a package
+ maintaining deps
+ consuming a package
+ programmatic api
+ assistance & contribution list

Ref #1371