Added project.get_operations() method.
Added test for get_operation(). Fixed test to work with 2.5
Fixed test_tutorial to work with Refine 2.5 . Main changes are due because now a new project generates column names starting from "Column 1" instead of "Column".
Added specific RefineProject.apply_operations_json() .
cleaning and removing unused imports
adding undo-redo command
fixing regression caused by urllib2_file removal
from urllib to requests. Removed urllib2_file
fixing export-rows, must return a file-like obj
Remove duplicate undo_redo