Tons of new stuff

Added pudl::time() returns a synchronized time() of when the class was
instantiated, so all db queries can store the same timestamp

Added to pudlMySql & pudlMySqlI: aesKey and aesDecrypt, compatible with
MySQL AES functions

pudlQuery::prefixColumns updated to support column aliases

pudlSession code generally cleaned up
PudlSession::write will now DELETE the session data from the database if
data is EMPTY

added puflShell - parses a custom JSON response from a shell script and
returns it as a collection of pudlShellResult objects