Bts-tools

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* [bts] read market parameters for bit20 feed from the blockchain

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* [bts] fetch correct silver price from Yahoo

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* [bts] fetch correct gold price from Yahoo

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* [all] added Telegram notification plugin
* [all] better subprocess management
* [bts] properly authenticate bit20 feed publication on the blockchain

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* [steem] new config var 'steem_dollar_adjustment' to help maintain SD stability,
price is published so that bias shows properly on steemd.com
* [steem] added Poloniex feed price provider for Steem
* [bts] new asset feeds: BTWTY, GRIDCOIN (currently disabled due to black swan)
* [bts] fixed precision bug when publishing feed price for expensive assets (eg: BTWTY, GOLD, ...)
* [all] updated seed nodes list, faster page rendering (cache seed nodes status)
* [all] general cleanup fixes, deploy script WIP

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* [all] pre-release of "bts deploy_node" command: complete setup of a
fresh VPS node, with bts/muse/steem client, nginx/uwsgi,
supervisor, etc.
* [all] added view for seed nodes of BTS, MUSE and STEEM networks
* [all] added world map view of connected peers and seed nodes along with
country detection (requires geoip2 account)
* [bts] added ARS (Argentine peso) market pegged asset
* [bts] reactivated GOLD and SILVER (Yahoo issue only temporary)
* [bts] removed Yunbi and CCEDK as feed providers for BTS/BTC
* [all] internal cleanups and refactoring, innumerable minor bug fixes