Added AzureBlobStorage adapter
- Decoupled Blob Factory
- PSR fixes
- Removed checksum auto calculation (causes weird problems in some circumstances)
- Added specs
- Some minor PSR fixes
- Now fails on major methods when container does not exists (as in amazonS3 adapter)
- Fixed `microsoft/windowsazure` version in `composer.json`
- Improved `keys()` method (thanks @Baachi)
- Added documentation and sample code on README file
- Improved `exists` performance
- Improved error management for exists method
- changed isDirectory to always return false
Merge pull request #206 from lmammino/azure-blob-storage

Added AzureBlobStorage adapter