Review proxy documentation and example code

Currently, documentation & example code for the proxy is spread between the tarball & the user manual. Below are current proxy-related files in the tarball:

./proxy/proxy.properties
./proxy/README
./proxy/examples/python/TestClient.py
./proxy/examples/python/TestNamespace.py
./proxy/examples/python/README
./proxy/examples/ruby/test_client.rb
./proxy/examples/ruby/README
./proxy/thrift/proxy.thrift

For 2.0, the number of proxy files in the tarball should be reduced to the files below.

./conf/templates/proxy.properties
./lib/proxy/proxy.thrift

All proxy documentation and example code should be moved to the Accumulo documentation on the website.