Support Lein's Test Filtering Syntax

[mlococo]

Quickie already supports filtering by namespace, but lein has several other options for filtering tests.

1. Run the :default selector by default: Common for projects to define their :default tests to be a subset of tests that excludes those that are slow and/or require external integrations to be available. Quickie currently runs all tests by default (or all tests in a given namespace), ignoring the :default selector.
2. Respect lein's built-in selectors: :all allows to run all tests even when the :default selector would only run a subset. :only allows selection of a list of tests as name.space/test-function.
3. Quickie already supports namespace selection, but it's semantics differ from lein's. Only :default tests should run by default. The quickie convention of selecting namespaces by regex instead of strict selection is awesome, though, and fully backward compatible with the strict selection that lein uses.

If Quickie offered compatibility with (or a superset of) lein's test selectors, it would be more intuitive to new user's who are familiar with lein test selection.