Merge pull request lmfit#195 from newville/master

add dump()/load() to Parameters class

Merge pull request lmfit#188 from newville/master

doc: add start of FAQ, and better links to support

change init values for success to True, errorbars to False

Merge pull request lmfit#162 from andyfaff/diffev

ENH: adding differential evolution as a fitting method

use py3.4 in upload script

updated README, using rst formatting

add example of using per-iteration callback

tweak doc html header

more doc on models

update version to 0.7.4