Too many warnings

[mivade]

Running the test suite results in an excessive amount of warnings. Some of these are ptsa warnings:

/home1/depalati/miniconda3/envs/ramutils_test/lib/python3.6/site-packages/ptsa/data/TimeSeriesX.py:264: UserWarning: The filtered method is not very flexible. Consider using filters in ptsa.data.filters instead.

which is a fairly useless warning that we should just suppress. Others are FutureWarnings such as

FutureWarning: Numpy has detected that you may be viewing or writing to an array returned by selecting multiple fields in a structured array.

This code may break in numpy 1.15 because this will return a view instead of a copy -- see release notes for details.

These should really be addressed!