Change existing 'metadata' to 'result_metadata'

There's about to be more kinds of meta floating around in here.
Add rapidjson third-party library.
Schema discovery WIP

query schema tables
rudimentary result processing (incomplete)
Static schema meta and API

no updates
Update .gitignore in schema_meta example
Add functions to get schema meta iterators directly.
Dynamic schema meta updates on Schema Change event
cbegin/cend are c++11 features

where did our std=c++98 go?
Schema metadata refactor
Merge branch 'CPP-153' into beta5

Conflicts:
	include/cassandra.h
	src/connection.cpp
	src/types.hpp