ENH: Add option to mount additional drives

[sandhujasmine]

Some of the blaze tests populate postgres data from CSV file in the
blaze/ project's directory. Use this option to mount it in docker so
posgres can read data when running those tests.

[sandhujasmine]

This allows us to define another mount point using -m so psql can find and load data for blaze tests.

To run blaze tests in test_postgresql_compute.py, let's fire up the postgres docker container and mount the test data location as well as the temp location to write output of tests:

provisioning.sh -t ~/tmp/docker/ -m ${BLAZE_PROJ_PATH}/blaze/blaze/examples/data restart

Next, set the env variables in the terminal. provisioning script writes a docker_info.txt file in ~/tmp/docker - copy & paste first 3 lines in terminal:

export POSTGRES_IP=192.168.99.100
export MONGO_IP=192.168.99.100
export POSTGRES_TMP_DIR=/Users/jsandhu/tmp/docker/

The following will now run tests that were previously skipping:
py.test -v test_postgresql_compute.py

[kwmsmith]

+1 Sorry that this one slipped through the cracks.