[Cosmos] Added create document, list documents and get document

Implemented features:

• Added Cosmos add document (both a plan &str and Serialize implementing struct).
• Added Cosmos list documents method.
• Added Cosmos get document method.
• Added more examples.

Hyper futures

Migrated all code to asynchronous hyper using Futures

Breaking changes

• Almost everything is now a future. So whenever you had a Result<A,AzureError> now you have impl FutureResult<A,AzureError>.

Updated references to bleeding edge

TODO

• Test the table code.
• Perform the E2E test.

Cosmos collection methods implementation

Implemented features:

• Added Cosmos' collection structures to interact with Cosmos collections.
• Added Cosmos' create collection method.
• Added Cosmos' list collections method.
• Added Cosmos' get collection method.
• Added Cosmos' delete collection method.
• Added Cosmos' replace collection method.

Updated references to bleeding edge

Cosmos database

Implemented features:

• Added Azure Cosmos DB support. Right now only database commands are implemented but the authentication frawework is in place. Both master keys and resource tokens are supported (see https://docs.microsoft.com/it-it/rest/api/documentdb/access-control-on-documentdb-resources?redirectedfrom=MSDN for more details).

• Added Cosmos client struct to interact with a Cosmos instance.

• Added create Cosmos database method.

• Added list Cosmos databases method.

• Added get Cosmos database method.

• Added delete Cosmos database method.

Minor bugfix release

Bugfix:

• Corrected a bug in BlockBlob put command that would not allow sending data. For more details see karataliu's pull request #16.

Enhancements:

• Expanded BlockBlob end-to-end tests.

Switch to Serde from rustc_serialize

Merge request #14

Refactoring

• Upgraded all the references to the state of the art. This includes Hyper with external TLS support.
• Removed rustc-serialize crate as it's now officially deprecated. Azure SDK for Rust now uses Serde. This closes issue 12.
• Added more end-to-end tests.
• Clippy'd all the code.

Send Event to Event Hub

Implemented features:

• Added Event Hub Send Event REST API implementation (as for https://msdn.microsoft.com/en-us/library/azure/dn790664.aspx).

Refactoring:

• Corrected azure::core::errors::AzureError to include the std::io::Error and xml::BuilderError instead of their to_string() result.
• Changed UnexpectedResult enum of azure::core::errors::AzureError to UnexpectedHTTPResult which holds an instance of azure::core::errors::UnexpectedHTTPResult instead of a tuple for better field description.

Added std::ops::DerefMut trait to azure::core::incompletevector::IncompleteVector

Bugfixes:

• Added std::ops::DerefMut trait to azure::core::incompletevector::IncompleteVector.
• Corrected README sample.

Refactoring:

• Renamed azure::core::ba512_range::BA512Range::len() function in azure::core::ba512_range::BA512Range::size() for better linting (len requires is_empty
  and was therefore misleading).

Implemented Blob::lease

Implemented features:

• Lease blob (https://msdn.microsoft.com/library/azure/ee691972.aspx).

Refactoring:

• Renamed azure::core::lease_id module in azure::core::lease.
• Moved lease enumerations in azure::core::lease module.

Bugfixes:

• Added the non-doc option for the bin test file:

[[bin]]
name = "main"
doc = false

Added crate exports in lib.rs

Implemented features:

• Added crate exports in lib.rs.