Remove redundant require statement from Rakefile.
Ignore all generated JS bundles, preview-mode flag, generated _config.yml, and most editor temp files.
Fix static reference to instance method in Compass' config.
Bring over a couple little things from master...
Merge pull request #1051 from MrJoy/patches_from_master

Bring over a couple little things from master...
Merge pull request #1047 from MrJoy/remove_redundant_require

Remove redundant require statement from Rakefile.
Merge pull request #1043 from MrJoy/gitignore_cleanup

Ignore all generated JS bundles, preview-mode flag, generated _config.yml, and most editor temp files.
Merge pull request #1042 from MrJoy/fix_compass_integration

Fix static reference to instance method in Compass' config.