World Quant Brain alpha utils

Uitls for mining alphas with world quant brain API. It has three commands:

1. crawl.py: Crawling fields from world quant brain API.
2. simulate.py: Send simulations to brain API.
3. collect.py: Collect simulation results from brain API.

Fields, simulations and alphas all stored in a local sqlite3 DB.

Examples:

1. Crawling fields

python crawl.py --db alpha.db --type MATRIX --dataset_id fundamental6

2. Generate simulation configs with sql in db

3. Send simulation to API

python simulate.py --db alpha.db --limit 100 --interval 60

4. Collect simulation results and alpha at same time

python collect.py --db alpha.db --interval 60