WebSocket++/0.3.0-alpha3

• Minor refactor to bundled sha1 library
• HTTP header comparisons are now case insensitive. #220, #275
• Refactors URI to be exception free and not use regular expressions. This
  eliminates the dependency on boost or C++11 regex libraries allowing native
  C++11 usage on GCC 4.4 and higher and significantly reduces staticly built
  binary sizes.
• Updates handling of Server and User-Agent headers to better handle custom
  settings and allow suppression of these headers for security purposes.
• Fix issue where pong timeout handler always fired. Thank you Steven Klassen
  for reporting this bug.
• Add ping and pong endpoint wrapper methods
• Add get_request() pass through method to connection to allow calling methods
  specific to the HTTP policy in use.
• Fix issue compile error with WEBSOCKETPP_STRICT_MASKING enabled and another
  issue where WEBSOCKETPP_STRICT_MASKING was not applied to incoming messages.
  Thank you Petter Norby for reporting and testing these bugs. #264
• Add additional macro guards for use with boost_config. Thank you breyed
  for testing and code. #261