Cleans up README
Cleans up README

Removes namespaces for simplicity, other touchups.

jkhoogland/cppitertools,ryanhaining/cppitertools,jkhoogland/cppitertools,tempbottle/cppitertools,jkhoogland/cppitertools,tempbottle/cppitertools,ryanhaining/cppitertools,ryanhaining/cppitertools,tempbottle/cppitertools