(CFACT-28) Add DMI facts for Linux and OSX.

Adding the following DMI facts for OSX:

- productname

Adding the following DMI facts for Linux:

- bios_vendor
- bios_version
- bios_release_date
- boardmanufacturer
- boardproductname
- boardserialnumber
- manufacturer
- productname
- serialnumber
- productuuid (renamed from facter-2 for clarity)
- chassistype (renamed from facter-2 for clarity)
Merge pull request #26 from peterhuene/facts/dmi

(CFACT-28) Add DMI facts for Linux and OSX.
(CFACT-20) Implement JSON output.

Implementing JSON output of facts.
Implementing map_value to support complex fact values.
Implementing integer_value to support integer types in JSON output.
Fixing output of existing integer types.
Normalizing facts names taken on the command line.
Moving version header into facter library.