Csnyder/reports

This PR adds a report module to rho. The report command has the same set of subcommands as profile.
A report is a named list of fields and an optional output file name. In addition this PR adds the initconfig command. This command generates a config file with a set of defaults. Presently this includes only the pack-scan report. Adding this command gives us the opportunity to provide these defaults, expand on them in future versions and perhaps use the command as an interactive set up for rho. 
While these changes are applicable to rho in general they also simplify the use of rho as  a replacement for pack-scan.

To do so now, do the following:
1) rho initconfig
2) Add at least one auth with root authority (i.e. rho auth add --name root --username root)
3) rho profile add --name mynetwork --hosts [csv of hostnames] --auth root
4) rho scan mynetwork --report pack-scan

Should this PR be merged I would be willing to do whatever is necessary to get the pack-scan users moved over and adjusted.

Side notes:
It occurs to me that I could add the system time the report is generated (or some other uniquely identifying info) to the filename of the report so as to remove the need to overwrite.