updated changelog
fixed error in documentation; partially addresses #531
ported run_script_usage_tests from qcli
added text on the source of this code
Merge pull request #1245 from gregcaporaso/issue-531-doc

fixed error in documentation; partially addresses #531
Merge pull request #1242 from gregcaporaso/issue-1019

updated default rdp_max_memory
Merge pull request #1250 from gregcaporaso/issue-950

updated so script usage test output from all_tests.py is more informative