added initial documentation, and settings to fix issue #30

Added initial documentation, and settings to fix issue #30

added the basic docstring for all template tags, but lack complete with documentation on what the function does, what the syntax (usage) and an advanced example

@dyve, please test my branch:

pip install -e git://github.com/luzfcb/django-bootstrap3.git@add-docs#egg=django-bootstrap3

this pullrequest, beyond documentation, also includes the following files:

HISTORY.rst - Contains the changelog
AUTHORS.rst - Contains all contributors from historic of commits
CONTRIBUTING.rst - Contains a contribuition guidelines