Add Change Issuer on Record

Note: Conflicts introduced by fec262eda55c40c874c7d10d9235fb139170832e resolved
fixed formatting
Clarification for unix timestamps, per issue #263
Set block number of P2SH and managed properties

Those features are already live, see:

https://github.com/mastercoin-MSC/mastercore/blob/mscore-0.0.8/src/mastercore.h#L97
https://github.com/mastercoin-MSC/mastercore/blob/mscore-0.0.8/src/mastercore.h#L98
missing zero fix
Remove other unimplemented features
Merge pull request #291 from dexX7/implemented-sync

Synchronize with master, further cleanup