Adding bolt flag into the command line options

[fcofdez]

Currently bolt is setup as True by default, so Graph is built using bolt, and in Neo4j versions < 3.0 cycli stops working.
A new flag, -b --bolt has been added to the command line set as False by default.

[nicolewhite]

cycli works in Neo4j < 3.0 because py2neo will just fall back to http. However I like the idea of making Bolt optional, because right now if you're on Neo4j >= 3.0 you're forced to use the protocol.

[nicolewhite]

I definitely want it to default to true, though, so maybe change it to a --no-bolt flag?

[nicolewhite]

Okay, I see now that it didn't work on Neo4j 2.0. cycli would start but would fail when you write a query. All that I needed to do was set the default bolt=None. py2neo will then auto-detect if it should use http or bolt.

I still think a --no-bolt flag would be useful, though, for people on Neo4j >= 3.0 who don't want to use bolt.

[ev-dev]

I've just submitted an alternative PR #66 with the changes @nicolewhite suggested

• Enabled Bolt connection by default (with a --no-bolt opt-out)
• Included a -B|--bolt-port flag that sets a non-default Bolt port when present