Refactor initialization of exclude options

* update option parser
* didn't add tests b/c i'm not using rvm and can't see an easy way to add commandline option parsing tests

Use RDoc inline-code formatting

support the PostGIS adapter

Fix typo

Fix typo in rake file setting, "try" should be "true"

add option to ignore columns matching a regex with -I or --ignore-columns

fix build spec for enum

Fix composite primary keys test

Fix #113 (for encoding comments generated by magic_encoding gem)

Remove excessive newline when annotation is put after code

Attempt model annotation only if table exists

Handle array column limits

Revise the warning in the README

See #122. I've revised the wording to placing the important text in the first sentence, and made the warning a bit more 2013-like by referencing VCS instead of backing files up.