Make encrypt and decrypt more flexible (#9)

* added options for decrypting to memory or stdout

* allowed any object supporting read and write to be used for encryption and decryption

* fixed some inconsistent variables

* added additional comments

* updated README

* made some adjustments for py3 compatibility

* increased version number and added six to setup dependencies

* improved temp dir creation

* checked for strings when reading from source objects

* resolved issues causing tests to fail with py3

* updated READMEs

Merge branch 'development'

Merge pull request #7 from dejonghe/development

Development

Merge branch 'development'

update readme

Add support for s3 file paths.

Merge pull request #1 from mattkenney/master

un-qualify boto3.client