Rename package reflecting support for different file formats

[sam81]

Besides preliminary support for EDF files I've started working on functions to read simple binary EGI files (https://drive.google.com/file/d/0B388xdH0Vxl2c284dTFRYnZKTXM/view?pref=2&pli=1). Rather than creating a separate package for EGI files I think it would make sense at this point to add these functions to this package and rename it in a way that reflects support for reading EEG signals in different file formats.

@codles do you have suggestions for possible names? The best I came up with is maybe EEGIO (for EEG input output), although certain file formats (e.g. EDF may be used for signals other than EEG).