Add a set of Python scripts that can be used as frontends
for the Flow Path measurements.

Typical usage:

1. Prepare the flows to measure
web/measurement_store_flow.py -f measurement_flows.txt

2. Install the flows with a single thread
web/measurement_install_paths.py 1

3. Obtain the time to install the flows
web/measurement_get_install_paths_time_nsec.py

4. Double-check the flows were installed into the Network MAP
   and the switches:
web/get_flow.py all

5. Repeat the experiment: delete the flows from the Network MAP
   and reinstall them with two threads:
web/delete_flow.py 1 100
web/get_flow.py all
web/measurement_install_paths.py 2
web/measurement_get_install_paths_time_nsec.py
web/get_flow.py all

6. End of experiment: clear the measurement flow state,
   the network map and switch flow state:
web/measurement_clear_all_paths.py
web/delete_flow.py 1 100
web/get_flow.py all
4 files changed