use numpy for pi value instead of hard coding
Merge branch 'master' of git://github.com/newville/lmfit-py
ENH: Add Model class and example.
Merge pull request #57 from danielballan/model

ENH: Add Model class and example.
Misc Model improvements...

* API: ``N=Parameter(value=7)`` is equivalent to ``N=Parameter(name='N', val
* CLN/PERF: Build residual only once, on instantiation.
* ENH: Allow models with no independent_vars.
* ENH: Support weighted fits.
* BUG: Copy parameters on input.
* ENH: Handle missing data.
* BUG: Accept pandas.Series equivalently to numpy.ndarray.
ENH: Add values property to Minimizer for convenient plotting.
BUG: Drop weights associated with dropped missing data.
ENH: Allow pandas data alignment inside residual.
Merge pull request #58 from danielballan/model

Misc Model improvements...
move github references from newville to lmfit
more fixes to doc
Merge branch 'master' of https://github.com/lmfit/lmfit-py
TRAVIS: some fixes
Revert "use numpy for pi value instead of hard coding"

This reverts commit a7ba050ae7952039e1d6b903d3fec99776ecaff8.
TRAVIS: build doc only with py2
Merge pull request #60 from sciunto/travis

Travis: some fixes