Set CC/CXX properly for gitian build
CheckBlock rule until 15-May for 10,000 BDB lock compatibility
Before 15 May, limit created block size to 500K
Checkpoint at first block in 11 March chain fork
Set version numbers for 0.8.1 release
Merge tag 'v0.8.1' into 0.8.0.eligius

0.8.1 release