Fix errors in source.sls

fix link to formula usage instructions

Fixed minor typo in nginx.ng.config.sls

Context parameter safety fixes

Tightened up some ng requisites.

Adds NG states

Add pillar item to disable using upstart-based services

Fixes GH saltstack-formulas/nginx-formula#14.

Updates to the readme.

fixing bug with common.sls that causes it to fail

move templates to the right place

remove extraneous nrpe include (fixes #8)

Fix source module iteration

* Fixing iteration for building nginx by source with respect
  to modules
* Adding `CHANGELOG.rst` and `VERSION` per https://groups.google.com/forum/#!topic/salt-users/zHguqsk-mds

Fix a filename and pillar key issue

* Ensure `common.sls` references correct template filename
* Use `pillar.get(...)` for message_do_not_modify with default

Re-organize nginx formula files

* Re-organize according to http://docs.saltstack.com/topics/conventions/formulas.html#writing-formulas

Added the ability to build from source or package, with luajit2 and openresty

Proper dictionary lookup

Restructure according to new guidelines.