filter out -1 values for lac and cid when doing a search by Cell record
added extra filtering so that CellMeasures with lac and cid = -1, are ignored
* added backfill code and new task into CELERY_TASKS
* added unit tests for backfill of cell tower information tasks
* clean up the backfill table when the task is complete
* added a schedule to run the backfill on a nightly basis
* Filter out records where MCC and MNC are -1 during the initial population of the cell_backfill table.
* switch the CellBackfill table to use a MEMORY storage backend in mysql
* Clean up of the cell_backfill table added after backfill task has completed
* reworked some of the test cases to check that no tower updates occur if the distance is too great
* reworked the backfill SELECT clause to pull only towers that look like they might be able to be corrected
* Changed tower matching to use (mcc, mnc, radio, psc) from (mcc, mnc, radio, pac)
* added an optional argument cell_measure_ids to the cell_location_update task
* added a new backfill_cell_location_update task that is invoked after the CellMeasure records are updated
* added a psc column to the Cell tower
* changed ichnaea.service.submit.schema to have -1 as the default value for mcc, mnc, lac, cid, psc and asu
* updated all testcases to the -1 default for mcc, mnc, lac, cid, psc and asu
* updated testcases to use new compute_matching_towers that uses Cell records instead of CellMeasure
merged from master
Merge commit '8cd648d745db16908a7af3d88f059556bdcfb7ae' into features/squashed_backfill
removed old TODO comment
fixed comment in the antipodal haversine test
moved radio argument to the earlier to match database schema
switched to use a defaultdict
fixed a typo in the NEAREST_DISTANCE constant
moved psc field ordering in the Cell model to match other models
cleaned up a query to pull CellMeasure records
removed duplicate key/value lookup with a loop using dict.items() instead
having a psc of -1 is acceptable for GSM/CDMA networks
added tests and code to cover github issue #70
Merge remote-tracking branch 'crankycoder/features/squashed_backfill'
review nitpicks, moved tests to backfill subpackage
Merge remote-tracking branch 'crankycoder/features/filter-invalid-lac-cid'