Made Content-Type a configuration-level option to better fix issue #63.

I still needed the Content-Type option, but I understand that if you include Content-Type in your
policy document, but don't include the corresponding field in your form, S3 will return 403's.

A better solution is to make it a configuration level option. I also added documentation
to clearly specify that you will have to add a Content-Type field to your form.
Add :will_include_content_type to CarrierWave configuration.
Add @colinyoung to contributors list
Add note to readme about sample application
lazy load UUID
Merge pull request #68 from filiptepper/master

lazy load UUID gem - thanks @filiptepper!
Add @filiptepper to contributors.
Update README.md for issue #43 & #59

https://github.com/dwilkie/carrierwave_direct/issues/43
https://github.com/dwilkie/carrierwave_direct/issues/59
Merge pull request #69 from rebyn/master

Update README.md for issue #43 & #59
Clarify readme submission by @rebyn.
Release v0.0.11 with new config option :will_include_content_type.
Merge remote-tracking branch 'upstream/master'