Feature: Logplex token from URL.

Related: #5

A logplex token can be placed in the user portion
of the URL. E.g. https://user@host/path. If no token
is passed to #puts, and there wasn't a token passed into
the initializer, we will rely on whatever is in the logplex url.
Merge pull request #6 from ryandotsmith/logplex-url-user

Feature: Logplex token from URL.