Change import statements to artiq_scan_framework

[philipkent]

Since the project is named artiq_scan_framework now instead of just scan_framework, people will be downloading the code to a folder named artiq_scan_framework. All of the examples, documentation, etc need to be updated so people don't have broken examples right off the bat. e.g. from artiq_scan_framework import * instead of from scan_framework import *

[philipkent]

Done, added to release_2 branch on linux machine. Needs to be merged into master branch and release-3 branch.