Update README.md
Added checkpoints in preparation for 1.8 release.
Corrected RSS URL in Gitian download config.
Update Gitian signature weights to reflect dev activity.
Merge pull request #609 from whitj00/patch-1

Add tip4commit to dogecoin
Update Win32 Gitian config to match changes in Linux.
Updated checkpoint statistics.
Merge pull request #610 from rnicoll/1.8-dev-checkpoint

Blockchain checkpoints 225000-339202
Merge pull request #611 from rnicoll/1.8-dev-gitian

Update Gitian download configuration
Adjust trigger conditions for safe mode to suit Dogecoin block time.

Values for triggering safe mode are time sensitive, and have not been
modified to take into account the differing block times between Bitcoin and
Dogecoin. This patch changes the interval across which a fork must exist to
override any other fork to 6 hours, and increases the number of blocks an
invalid fork must have before it trips safe mode.

This should help mitigate disruption in the 1.7/1.8 hard fork, but miners will
still need to run with -disablesafemode for the preceeding and following 2-3
days to be sure.
Update the wallet logo to represent 1.8.
Merge pull request #615 from rnicoll/1.8-dev-logo

Update the wallet logo to represent 1.8
Merge pull request #614 from rnicoll/1.8-dev-forkwarn

Adjust trigger conditions for safe mode to suit Dogecoin block time