NOJIRA Added fallback call for hex2bin() in ZipFile class

As it turns out, hex2bin() requires PHP 5.4 and we might not want to
discard PHP 5.3 just yet as it’s still the default Linux distros like
RedHat.
NOJIRA Fixed a couple of installer/configuration exporter issues

1) Records imported by scripts can have pretty long idnos, but we
enforce a maximum length of 30 in profile.xsd. The config exporter now
truncates them accordingly.
2) There were a couple of illegal array operations in the setting
processing code in the Installer where we would blindly try to access
keys in arrays without checking whether they exist.
NOJIRA Cleaned up and commented the setting processing code in the Installer

It’s still a train wreck but at least kind of makes sense now.
Merge branch 'master' of https://github.com/collectiveaccess/providence