ENH: Add CTPS method to detect artifacts

from juelich import ctps ;-)

advanced ECG component detection using phase statistics.

I implemented this with @jdammers based on his IDL code.

![screen shot 2014-06-16 at 11 22 25 am](https://cloud.githubusercontent.com/assets/1908618/3285264/d349c7cc-f537-11e3-94b6-3505ab80d3bb.png)

See how much clearer the outliers are produced by this metric.

Here's the correlation result.

![screen shot 2014-06-16 at 11 24 32 am](https://cloud.githubusercontent.com/assets/1908618/3285278/1406aa32-f538-11e3-8c7d-b101746c2266.png)

The difference is most striking when ICA unmixes additional components related to the p-wave.

`ch_name` docstring needs updating. Also, just noticed that `_make_ecg` always uses all channels instead of either `mag` or `grad` (see line 288 in `ecg.py`).