init of xraylib_wrap branch
add sub class of XrayLibWrap
add doc for options
more clean up
more overloading functions, eq, gt, lt...
use functools
change terms of element and info_type, use info_type for subclass for other cases in xraylib and remove optional for incident energy
use all attribute to output all the line information
ENH: Fixed logging in nsls2/__init__.py
add all rst file for fitting
clean bugs in doc
MNT: Move gridder into core from recip

It doesn't make sense for the gridder to be in recip as there's
is nothing actually unique to reciprocal space in the gridder.
It makes more sense for it to be in core.
MNT: Realized I didn't move the corresponding gridder tests

- Moved the gridder tests from test_recip.py to test_core.py
- Put the ctrans import back in to recip.py
ENH: First attempt at coveralls integration
BUG: ...stupid typo
MNT: Attempting coveralls.io with nosetests
ENH: Added coveralls badge
MNT: reset .travis to run 'run_tests.py'

- fixed run_tests.py to run nosetests with coverage just on the
  nsls2 package.
DOC : added api_changes file
ENH : added bin edges -> bin centers function

 - convince function + test