Merge pull request #12 from zonca/bls_vec

first implementation of vectorized bls
- Started some re-organization of the repo.
- Renamed Andrea's program to something more explicit.

- Started work on getting the sim_lc folder into a module directory.  You can now run drive_make_lc from the parent directory by using python -m sim_lc.drive_make_lc

- Was missing a coding stub that caused sim_lc/make_lc.py to crash.  Added that in as a "pass" function so that it quietly runs to completeness.
- Intermediate check-in of unit test for bls_pulse{_vec}.
gitignore
bls_pulse_vec per segment

Now bls_pulse_vec outputs SR segment by segment,
also accepts only 1 period instead of a list.
See #11.