[URI] Provide ability for query vars manipulation

[lonnieezell]

Currently, query vars are only represented as simple strings in both output and input. We need ways to manipulate the values that are used.

• retrieve a whitelisted set of query values (getQuery('only', ['foo', 'bar']))
• retrieve all query vars in the string except for a blacklist (getQuery('except', ['foo']))
• stripQueryVars('foo', 'bar', 'baz')
• `addQueryVar('foo', 'bar');

Enhancement Checklist:

• Component(s) modified
• Unit testing updated
• User guide updated
• Securely signed commits
• Conforms to style guide

[lonnieezell]

These changes are done, and will be submitted along with the Pagination library.