first implementation of signed letters
add base64 encoding
add letter namespace and Letter class
add Debase64 utility function
fix debase64
add test case
add letter verification logic
refactor whitelist verification
first complete version of letter sign & verify
minor cosmetics
erlang fixes
add support for CVMFS_AUTO_TAG
support removing multiple tags in a single publish operation
add CVMFS_REPOSITORY_DATE
use ISO-8601 date
move guinea pig tar balls to common location
parse iso8601 timestamp string
factor out repo resurrection functions for code reuse
factor out legacy repo cleanup for code reuse
FIX: typo in status print out