Add support for configuration file, add all static AIDs

The configuration file found at /etc/libnss-aid.conf can be used fo fine-tune
parameters used in the NSS module, such as to enumerate static AIDs. Other
options will be added at a later time as required.

The full range of static Android IDs are now supported and will be resolved.

The Makefile now includes two extra targets, uninstall and purge, to remove
libnss-aid from the system or purge the configuration files as well,
respectively.