Adding more DBaaS MySQL metrics
Expanding query logic to handle column names as keys

The original query logic assumed that only statements such as
'show status' would be run. These queries only return two cols
per row, Variable_Name and Value. The stat_map used the value of
the key Variable_Name as the header. To accommodate more complex
'show' queries, the logic had to be expanded so that some queries
can still behave like this, but others can behave such that the
actual column name was the stat_map identifier, not the value
within that column.
Merge pull request #535 from hub-cap/refactor_query_logic

Refactor query logic