Update INSTALL file
Update CHANGELOG for 0.0.8 release
Update git tag to reference new GnuPG key (0xD255D3F5C868227F)

Key fingerprint = D2C6 7D20 E9C3 6C2A C5FE  74A2 D255 D3F5 C868 227F
Update git tag to reference new GnuPG key in Makefile
update HTTPS user_agent to reflect version
Update CHANGELOG for 0.0.8 release
hard code subkey 0x1801A819