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
Merge pull request #36 from erikd/postgres

Add -fwarn-tabs to ghc-options.
Move keter postgres configuration under plugins.

This fixes snoyberg/keter#46 for v1.0 Keter config syntax.