Refactor execute stuff to make it support pluggable compute backends

Test Plan: -

Reviewers: marcua

Reviewed By: marcua

Differential Revision: https://phabricator.locu.com/D7714
Deployment readme

Test Plan: -

Reviewers: lydia, dyschultz, marcua

Reviewed By: marcua

Differential Revision: https://phabricator.locu.com/D7739
Changes for PyPI

Test Plan: -

Reviewers: lydia, dyschultz, marcua

Reviewed By: marcua

Differential Revision: https://phabricator.locu.com/D7752
Add pykronos to requirements.txt and remove symlinks

Test Plan: -

Reviewers: lydia, dyschultz, marcua

Reviewed By: marcua

Differential Revision: https://phabricator.locu.com/D7756
Date functions, test data load script, fancy math operators for Value

Test Plan: -

Reviewers: dyschultz, lydia, marcua

Reviewed By: marcua

Differential Revision: https://phabricator.locu.com/D7749
Remove unused imports
Fix LICENSE file, add AUTHORS
Fix LICENSE file, add AUTHORS
Fix LICENSE file, add AUTHORS
Merge pull request #115 from Locu/fix-license

Fix license, add authors file
+x load_test_elections_data.py script
Merge branch 'master' of github.com:Locu/chronology
Pass PyCodeErrors through to the user without re-wrapping
Bump cassandra version
Add test for checking start/end time inclusivity in delete and update documentation

Test Plan: -

Reviewers: marcua

Reviewed By: marcua

Differential Revision: https://phabricator.locu.com/D7808
Fix scheduler imports
Update Kronos README with info on kronosd
Fix symlink
Quick wording change
Fix bug in DatePart