Include error in email

If autopkg encounters an error during the run, it will include that information in the e-mail.

I've also moved all of the e-mail logic out of the LGAutoPkgRunner class and into the LGEmailer class.  So now there's a new method in LGEmailer

```Obective-c
- (void)sendEmailForReport:(NSDictionary *)report error:(NSError *)error;
```
Which converts the dictionary into a format appropriate for an email message

Also note I've changed the version string by default to "Version Undetected" rather than "N/A" which may be closer to what it should be, since it's always applicable.  @futureimperfect  there's probably an even better string, I'll leave it to he with the grammatical name to insert.