Fixes to ensure SAMLRequest compatibility with various IdPs

Including OneLogin, Okta, AD FS, and simplesamlphp.

* Re-instated raw deflation of request since some IdPs could not handle zlib headers
* Added SAMLEncoding parameter to hint encoding to IdPs that pay attention to it
* Removed extraneous namespacing from SAMLRequest
* Removed extraneous AuthnRequestContext from SAMLRequest due to problems with AD FS

Bumped revision to 0.1.11