Applied fix for https://github.com/mastercoin-MSC/mastercoin-tools/issues/24 described in https://github.com/mastercoin-MSC/mastercoin-tools/issues/24#issuecomment-40338334
If getting a single transaction from obelisk fails, try again in case it was an intermittent error.
When querying block height, output values, or transaction content from obelisk, if we are unable to get the data for some reason we can try again from blockr.io, as a backup.
Added a secondary exodus deadline, as described in https://github.com/mastercoin-MSC/mastercoin-tools/issues/24#issuecomment-40338334
Merge #41.