Added test routine for LYRA instrument utilities and added an additional utility

I added a test file to sunpy/tests/instr/ for testing the LYRA utilities in sunpyinstr/lyra.py. Pull request includes:

  - Added an extra utility to sunpy/instr/lyra.py which takes an input timeseries and splits it up into sub-series using the results of a LYTAF query.

  - Added test_lyra to the tests package in sunpy/sunpy/tests/instr/. The test will download the LYTAF database to a temporary directory and perform a query on it, testing that the result of the query has the correct form.

  - Temporarily changed the LYTAF download method in download_lytaf_database to directly use urllib.retrieve so that the terminal is blocked during the database download (alternative suggestions welcome!).

Addresses issue #650