rename access control section
rearrange sections

* all configuration documentation consolidated under one section
* other sections shifted around a bit based on my (@jjb's) subjective judgement of importance

n.b. there is redundancy in the configuration options section, which will be consolidated
in a subsequent commit
consolidate rails initializer documentation
consolidated documentation of configuration options
remove note about new home

which is irrelevant in this repo...
create features list

and move description of db profiling there
Learn more section
documentation for middleware reordering recipe

addresses #45
Merge pull request #46 from jjb/readme-improvements

Readme improvements