Add boto calling_format support

[msumit]

Boto throws SSL exception for buckets which have dots (.) in their name when used with its default calling format (SubdomainCallingFormat). Adding support to accept other calling formats like 'OrdinaryCallingFormat' and 'VHostCallingFormat'.

[landscape-bot]

Repository health decreased by 0.01% when pulling 6482b3b on msumit:boto_calling_format into 0e325d9 on airbnb:master.

• 2 new problems were found (including 0 errors and 0 code smells).
• No problems were fixed.

[bolkedebruin]

Thanks for the contribution! Please follow these http://chris.beams.io/posts/git-commit/ guidelines for your commit message. It helps creating changelogs and release notes in the future. In this case a more descriptive title (boto is an underlying technology) and and please make it imperative (add vs adding).

And please add some tests so we get increased coverage instead of decreased. Thanks!

[coveralls]

Coverage decreased (-0.05%) to 66.328% when pulling 6482b3b7ddd4954e15a11ce6e1abae92f0b77b65 on msumit:boto_calling_format into 0e325d9 on airbnb:master.

[bolkedebruin]

Please update your commit message (not the PR title) to something like "Add support for calling_format from boto to S3_Hook" and I'll merge. Bonus points if you update the tests and coverage increases. Thanks.

[landscape-bot]

Repository health decreased by 2% when pulling 16f53cc on msumit:boto_calling_format into 0d9c0ac on airbnb:master.

• 116 new problems were found (including 3 errors and 50 code smells).
• 93 problems were fixed (including 4 errors and 42 code smells).

[msumit]

Changed the commit message, but couldn't think of a way to test the proposed changes.

[coveralls]

Coverage decreased (-0.08%) to 67.023% when pulling 16f53cc on msumit:boto_calling_format into 0d9c0ac on airbnb:master.