Better Bower + Rails config

Avoid adding bootstrap-sass to global asset load path
fix readme typo
Readme Bower + Rails: better precompile regexp
Fix Readme typo
readme
Readme link fix
rake convert
bump version to v3.3.1
Remove Rails 3.2 instructions
readme mincer typo [ci skip]
Split parent selector parts #763

before:

    +input-size('.input-sm, .form-group-sm .form-control', ...)

after:

    +input-size('.input-sm', ...)
    +input-size('.form-group-sm .from-control', ...)
Use dist/js/bootstrap.js from upstream #777

Before we compiled bootstrap.js by concatenating individual files.
This copies the file from upstream for maximum compatibility.
rake convert