Merge pull request #588 from BrandonGilchrist/feature/delayed-crowdsale-docs

Add docs for DelayedClaimable

docs/source/delayedclaimable.rst

+DelayedClaimable
+=============================================
+Extension for the Claimable contract, where the ownership needs to be claimed before/after a certain block number.
+
+setLimits(uint256 _start, uint256 _end) onlyOwner
+""""""""""""""""""""""""""""""""""""""
+Specifies the time period during which a pending owner can claim ownership.
+
+
+claimOwnership( ) onlyPendingOwner
+""""""""""""""""""""""""""""""""""""""
+
+Completes transfer of ownership by setting pending owner as the new owner.