Fix For "BSD 'date' does not have the -R option"

modified date calls on lines 514, 515, 531, and 628 to use
+"%a, %d %b %Y %H:%M:%S %z"
in place of
-R
for compatibility with BSD systems.

This commit has not been tested, but should work.
Merge pull request #15 from subtleq/master

Potential Fix For Issue #3