Update README.md (RIPD-601)
API for improved Unit Testing (RIPD-432):

* Added new test APIs allowing easy ways to create ledgers, apply
  transactions to them, close and advance them.

* Moved Ledger tests from Ledger.cpp to Ledger.test.cpp.

* Changed several TransactionEngine log priorities from lsINFO to lsDEBUG to
  reduce unnecessary verbosity in the log messages while running these tests.

* Moved LedgerConsensus:applyTransactions from a private member function to a
  free function so that it could be accessed externally, and without having to
  reference a LedgerConsensus object.  This was done to facilitate the new
  testing API.
New ripple::TestSuite with method expectEquals().
Cull duplicate/unused code in RippleAddress:

Deduplicate a call to GeneratePublicDeterministicKey().
Remove unused member functions.
Always initialize LedgerHandler options field
Support a "no_server" flag in test config:
* Will use a running instance of rippled (possibly in a debugger).
* Modify all tests to respect the server_default value.
* Fail test if new account already exists and has a balance.
* README.md with instructions for advanced test debugging, particularly using no_server.
Split off CheckLibraryVersions.test.cpp.
Remove unused sitefiles module
Reduce Beast dependencies by leveraging C++11 features:

* Remove beast::Atomic (RIPD-728):
  * Use std-provided alternatives
  * Eliminate atomic variables where possible

* Cleanup beast::Thread interface:
  * Use std::string instead of beast::String
  * Remove unused functions and parameters

* Remove unused code:
  * beast::ThreadLocalValue
  * beast::ServiceQueue
Remove legacy LoadTypes (RIPD-365)
Fix undefined behavior