Removed the isdigit() check for the Snipe asset tag as this creates issues when a non-digit prefix is used.

Fix asset tag only updating when number

Exceptions aren't very likely during this initialization step, but if
they occur the user definitely wants to know about them.

I fixed two condition checks to make sure the data from Jamf and the data from Snipe are aligned.

These are successfully set attributes, but showing as failing because the data doesn't line up at time of comparison.

Snipe adds " 00:00:00" to the date, and json reports None for a blank value while the Jamf data contains an empty string.

By doing these two conditional checks, I stop getting 3 warnings for ever machine updating that has these attributes updating in the case of purchase date, or not changing as is the case with my empty custom attributes.

Fixed two condition checks for confirming updating fields

Print exceptions during is-up detection

This is helpful to run the same script in multiple environments, where
adapting the `settings.conf` file might not be possible or desirable.

This moves the sample settings.conf file to settings.conf.example to
help users and developers avoid accidentally committing and publishing
their credentials.

Resolves: grokability#68