[RFR] Optimize build process

[jpetitcolas]

Add better uglification, optimize Webpack internal ids and remove eventually duplicated code.

Before:

$ ls -lh build/
total 2,8M
-rw-r--r-- 1 jpetitcolas jpetitcolas 1,4M May 29 10:01 ng-admin.min.css
-rw-r--r-- 1 jpetitcolas jpetitcolas 814K May 29 10:01 ng-admin.min.js
-rw-r--r-- 1 jpetitcolas jpetitcolas 7,0K May 29 10:01 ng-admin-only.min.css
-rw-r--r-- 1 jpetitcolas jpetitcolas 593K May 29 10:01 ng-admin-only.min.js

After:

$ ls -lh build/
total 2,7M
-rw-r--r-- 1 jpetitcolas jpetitcolas 1,4M May 29 10:02 ng-admin.min.css
-rw-r--r-- 1 jpetitcolas jpetitcolas 796K May 29 10:02 ng-admin.min.js
-rw-r--r-- 1 jpetitcolas jpetitcolas 7,0K May 29 10:02 ng-admin-only.min.css
-rw-r--r-- 1 jpetitcolas jpetitcolas 575K May 29 10:02 ng-admin-only.min.js

[manuquentin]

Thanks for polar bears !

[jpetitcolas]

[jeromemacias]

Please do not commit built files to avoid conflict.

[jeromemacias]

Can you rebase ?