Adding remote MySQL functionality

Adding tests and code to verify that the MySQL database on Repository is
accessible and responds to a sample command ("show tables;"). The
"sample_output" value comes from running the command manually and cutting-
and-pasting the result.
Changing config for database access

Use the production configuration for Repository rather than the
development configuration.
Modifying output file tests

Changing the "runs MySQL client" and "captures MySQL client output" to increase
accuracy of the tests. Verifying that MySQL client ran uses the File method
exist? to simply check that the output file was created. Updating the variable
labels to reflect what's actually being tested (i.e. "file_contents").
Adding a test to run MySQL using the generated infile

The test instantiates an object and then calls the `run_mysql` method. The
output is compared to the var `sample_output` which doesn't exist yet.
Added sample output to SQL infile test

Ran the MySQL command manually to retrieve the expected output. Sample data
added to test for verification.