Added smart property fundraisers, improvements to other future features

Also various cleanup and clarifications
Clarification requested by Marv
Added best practices for handling bitcoin reorgs
How to handle transaction version numbers
Better summary of how to handle version 0 sell offers
Some of the changes needed after reading Marv's comments about my pull request
More changes from Marv's comments
More changes from Marv's comments
More changes from Marv's comments
Adding a general purpose data field which can be used to store contract hash for a property (proof of existence)
Merge pull request #52 from dacoinminster/master

Added smart property fundraisers, improvements to other future features