RPC: addnode, getaddednodeinfo, removeaddress

Перенёс 3 RPC команды из Bitcoin Core в Novacoin. 
1) addnode
2) getaddednodeinfo
3) removeaddress

addnode:
https://github.com/bitcoin/bitcoin/commit/72a348fd9a7015aa039f9cbdc9166f388f4725e0
https://github.com/bitcoin/bitcoin/commit/b641c9cd217f7789726bb25ab87cd35e2e5fcaad
https://github.com/bitcoin/bitcoin/commit/f2bd6c28e6bddd75d56d580c28f45d2a8be065ab
https://github.com/bitcoin/bitcoin/commit/f339e9e3391465de4921aea3194f3021016f07d1
https://github.com/bitcoin/bitcoin/commit/74088e862e29821562652986c6bd7c14c3783327

getaddednodeinfo:
https://github.com/bitcoin/bitcoin/commit/67a11bd6c5c28edc5f24574595380c1ddf8becf4

removeaddress:
https://github.com/paveljanik/bitcoin/commit/efc79d1bd19163dd0bdf0940a6528096c78f787a
https://github.com/bitcoin/bitcoin/commit/939ed97373fdea0e8ecb173f1c22eb53b9f90bb6
https://github.com/bitcoin/bitcoin/commit/ccca27a788fe1ae13661308243c20a1d7a3d0074