Several improvements and refactoring

Account
* get_bandwidth refactored
* get_account_bandwidth added
Cli
* power added for showing vote power and bandwidth
Steem
* Improvements and refactoring for get_config, get_network, get_hardfork_properties, get_current_median_history, get_reward_funds, get_feed_history, get_reserve_ratio and get_dynamic_global_properties
Steemnoderpc
* get_network moved to graphenerpc
Chains
* removed to beemgraphenebase/chains.py
Unit tests
* add unit test for power for cli
* golos test reduced
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