add debconf tool to manage postgresql.conf file modification
tests/engine2_test:

Renamed to `engine_test.py`
engine:

Added functionality to parse sites from a CSV file into the `sites` param.
tests/engine_test:

Added a couple of test cases to exercise reading sites from a sites CSV when
parsing params.
debian/postinst: some comment fixed
Merge pull request #1113 from larsbutler/sites-csv

Read `sites` from `sites_csv`

[r=matley] [f=1097618]
python-h5py removed as dependency
unneeded python-gflags and python-matplotlib packages dependencies removed
Typo fixed in comments
Merge branch 'pkg-interact'
Merge pull request #1115 from matley/order-by-points-to-compute-exposure

Fix a "reproducibility" issue when getting hazard sites from exposure
Merge branch 'master' of https://github.com/gem/oq-engine into risk-fractions-event-based