Add a section on using Gremlin from Python

[krlawrence]

Need to add coverage of submitting both text and ByteCode queries from the Python GLV client.

[krlawrence]

Need to add coverage of GremlinPython and iPythonGremlin.

[krlawrence]

The example code that this work can build upon is now created under issue #121

[krlawrence]

Also add notes that discuss common pitfalls people run into migrating from Gremlin Console queries to Python:

1. Remembering to use a terminal step like iterate,next & toList
2. Discovering the reserved words that need a suffix added such as "as_"
3. Ensuring global replacements of keywords like range are avoided (I believe the clients have already had this addressed)
4. The fact that Python dicts cannot have immutable keys so a group() step that generates, say, as map as the key will fail unless special action is taken.
5. Taking not that certain things like per query timeout need the app to build its own Request object.