[POC] Coin-based Classes

* Added coin_base class to extend from
* Defaults in coin_base apply for scrypt/sha256d
* Added coin_scrypt and coin_sha256d that extend without changes
* Updated statistics class to use new coin class calls

Addresses #1953
[POC] Replaced config target bits with coin base

* Do not auto-set target bits via autoloader
* Use coin_base to declare target_bits
* Adjust target_bits in each coin_algo class instead

Addresses #1953
[FIX] Access to protected var
[REMOVED] Code Debug output
[UPDATE] Blocks overview est shares
Merge branch 'development' into coin-plugin-system
[MOVED] Coin Classes into own folder
Merge branch 'development' into coin-plugin-system
[FIX] Proper getTargetBits call
[FIX] Worker class
[FIX] Target Bits on Dashboard
Merge pull request #1955 from MPOS/coin-plugin-system

Coin plugin system