Unified data-reduction suite

You may want to pull this to a new branch yourself...

This branch unifies the data-processing from the different telescopes. It is tested and works.

Note, I need to spend some time adding docstrings. 

The new structure:
*trials/vlbi_b1919/reduce_data.py : the new reduction routine. run with '-h' option for help. 
                                                 the default runs analogous to 'aro.py'
*folding/fold.py : the generalized folding/dedispersing routine. There are still some 'if' statements that are     telescope-dependant I am working on getting rid of

*folding/filehandler.py : the filehandlers for the different telescopes

*folding/psrfits_tools.py : read the psrfits definition file (fitsdef.txt) and provide an HDUList class so files act like
                                  fits files.

*trials/vlbi_b1919/observations.py : parse ConfigObj file 'observations.conf' which lists all the observations and returns the information in a useful format (a telescope object with observation objects).