Load Operators Based on Database Connection

[aguynamedryan]

As part of #283, I had intended for each Database instance to load its operators from the database connection provided to that instance.

It does not look like that is happening.

So, going forward, when a ConceptQL::Database instance is given a database connection, the Database should load the operators for all Query instances from the provided database.

At the moment it seems ConceptQL loads all instances from the LEXICON_URL connection instead, and even then I saw some intermittent behavior where that connection was ignored and other connections were used instead.