Adds ability to specify redirect location for files

Other than the new redirection feature, pull request changes `s3` object for `cap deploy` task from 
```ruby
AWS::S3
```
to
```ruby
AWS::S3::Client
```
This change is intentional, as former class doesn't allow to specify redirection metadata header in `S3Object#write` method, thus it was necessary to use `S3Client#put_object` method for upload.

Also there are minor refactorings, renamings and bug fixes to various parts of gem.