Add test for 7188
Insert data during upgrade
Lower RF to 2. Increase write count.

Based on Aleksey's recommendations.
Restrict 1.2->2.0 upgrade tests to being run on 2.0 or higher
Add comments explaining upgrade path
Merge branch 'master' into 7188

Conflicts:
	upgrade_supercolumns_test.py
datahelp.py allow setting consistency level
update paging tests read and write at cl.all

I did this wrong originally and it made the tests a bit flaky.
tests were initially reading and writing at CL.one, so some race
conditions could cause a test failiure.
Merge pull request #109 from riptano/paging_test_CL

make paging tests less flaky with cl.ALL
udf test
change to since(3.0)
Stop/start nodes when upgrading the version
fix for #108
upgrade test, flush nodes before shutting down
Merge pull request #96 from riptano/7188

7188
Reduce number of writes to lower test time
Test for 8206
paging tests should not use uuid1
collisions were causing test failures
Test for #8156
Merge pull request #110 from riptano/paging_uuid_fix

paging tests should not use uuid1