Instructions for creating an OS X native development environment

Probably not 100% complete yet, but covers enough to pass all specs.

NOTE: requires either libXML2 2.7.6 or the separately submitted fix to
pretty_text_spec.rb
The wrong version actually got moved to this branch when I tried to clean some things up. This version should be correct :-)
replace CRLF with LF
prevent crlf on yml files
fix some typos in English strings
cs translation update
Post processing of images adds prefix second time when post processing a post with one or more images if running with a prefix
Fix for reply to user avatar and picture uploading not working when editing post with discourse running in a prefix
Sync folder now specifies id

Vagrant 1.1.5 seems to think we are overriding a previous shared folder
in our script. Passing the id solves this.
Merge pull request #642 from mshappe/mac-native-guide-fixed

Instructions for creating an OS X native development environment
Merge pull request #657 from kubabrecka/master

Replace CRLF with LF
Merge pull request #658 from ZogStriP/prevent-crlf-on-yml-files

prevent crlf on yml files
Merge pull request #663 from kubabrecka/cs_update29

cs translation update
Merge pull request #662 from kubabrecka/en_typos

fix some typos in English strings
Merge pull request #660 from wojciechka/cooked_images_double_prefix

Post processing of images adds prefix second time
Merge pull request #661 from wojciechka/prefix_fixes

Fix for reply to user avatar and picture uploading not working when editing post when using prefix