Travis: disable gdb thread event logging

Attempt 2
Remove Jenkins CI build status badge

This isn't used any more is it?
Fix typos: tecMASTER_DISABLED, tecNO_REGULAR_KEY
Add C++11 noexcept compatibility for VS2013
Add beast::buffer_view
Add ripple::byte_view, ripple::const_byte_view
Move MultiSocket, RippleSSLContext to common module
Add std::integer_sequence C++14 compatibility
Refactor beast::asio:
* New tools for completion handlers:
  - wrap_handler provides composed io_service execution guarantees.
  - bind_handler rebinds arguments to handlers.
  - shared_handler type-erases any completion handler.
  - buffer_sequence type-erases templated BufferSequences
  - abstract_socket replaces Socket
  - socket_wrapper replaces SocketWrapper
  - beast::asio placeholders to work with std::bind

* Removed obsolete classes and functions
  - AbstractHandler
  - ComposedAsyncOperation
  - SharedFunction
  - SharedHandler
  - SharedHandlerAllocator
  - SharedHandlerPtr
  - SharedHandlerType
  - SocketBase
  - SocketWrapperStrand
  - wrapHandler

* Refactored classes to use new tools
  - abstract_socket
  - socket_wrapper
  - HandshakeDetector
  - HttpClientType

* Miscellanous tidying
  - socket classes moved to beast::asio namespace
  - beast asio files provide their own namespace declaration.
  - Fix IsCallPossible conflicting template parameter name
  - Use <boost/get_pointer.hpp> for C++11 compatibility.
  - Remove extraneous include path from build environment.
Set version to 0.23.0
Better diagnostics for SSL certificate failures
Remove obsolete support scripts
Build system improvements:

* Reduce console verbosity.
* Display configured build environment.
* Log build environment and commands in rippled-build.log.
* When compiling under Travis:
  - define TRAVIS_CI_BUILD for C and C++ code.
  - define RIPPLE_MASTER_BUILD for builds made against
    the official Ripple repository.
Misc cleanups:
Prepare beast for switching to libc++'s c++14 in the future.
Guard beast's std::equal with BEAST_NO_CXX14_COMPATIBILITY.
Remove ineffectual 'const' from two places where it was
having no impact: declaring an alias to a reference const.
Consider renaming SField::ref to cref.
Distribute namespace beast through headers in beast_core.h
Distribute namespace beast through src's in beast_core.cpp
War on using declarations.