Provide a simpler implementation of function parse-line.
Merge pull request #6 from asemt/smplfy_fnc_parse-line

Provide a simpler implementation of function parse-line.
Pull log line pattern out of let statement

Only have the log line pattern be declared once,
instead of every time for the method call.

Fixes #4
Add methods for millis, second, and 15-minutes

Added methods to get the different timestamp resolutions
in a way that reads nicely when passed to the count-entries
function for the :by argument.

Now supports timestamp-millis, timestamp-second, and
timestamp-15-minutes, as well as updating the tests to include
the additional methods.