Upgrade bootstrap.css to v3.2.0

Drop normalize.css since bootstrap.css already contains it.
Add some Bootstrap styles
Show Bootstrap icons in links and button
Remove bootstrap.js since it is not used in the scaffold
Merge branch 'bootstrap3' of https://github.com/iquiw/yesod-scaffold into postgres
Add -fwarn-tabs to ghc-options.

Closes: #35