Added a unit test that would buy/sell a small amount of RAM and a large
amount of RAM.  This test showed unexpected behavior due to attempting
to sell over 2^32 RAM.  I updated the sellram action to enable selling
more than 2^32 bytes at once.

Test results show that for both large and small quantities, the user
losses a small amount of tokens and does not profit.

(cherry picked from commit 10273fa2d180f81769516b507bfdff68f06b7f87)

- update system contract with setram that properly updates market
pricing

- buy & sell ram using bancor algorithm
- ram is no longer delgated
- fixed warning with double secondary index
- add block_timestamp_type

- udpate system contract to set initial account bw to 0
- update system contract to process new on block header
- update cleos api and get info api

Also, it now checks to ensure the proposed producer schedule would actually change the schedule.

singleton takes code and scope as runtime-parameters, global_state_singleton restored in system contract, hack to prevent llvm-linker from removing apply function #2227

system contract refactoring - move code from .hpp to .cpp, use new dispatcher (some code temporarily commented out) #2227