Update README.rst

updated travis config to use latest zipline when building container

removed pandas-datareader from stockbot requirements

updated zipline and pandas-datareader dependencies to latest

added system label to order_meta context

removed input data from meta store because memory

added meta data capture into context for debugging and analysis

fixed py2/3 compatibility issue with zipline run_algo

revised order targets and implemented max portfolio sizing; added unit tests for algos

fixed adx interval bug in adx_di_so

added option for adx ranking interval other than every iteration

fixed bug in symbol validator

updated zipline to latest

fixed init bugs

added symbol validator to core algo init and revised algo unit tests