Fix #913: Properly copy MappingJsonFactory features

[dsw2127]

Fixes issue with copying MappingJsonFactory (and therefore ObjectMapper) not properly copying features.

#913

[cowtowncoder]

Makes sense, yes. I'd be happy to merge this patch.

One formality we unfortunately need is a filled Contributor License Agreement, which can be found from here:

https://github.com/FasterXML/jackson/blob/master/contributor-agreement.pdf

(or, corporate alternative https://github.com/FasterXML/jackson/blob/master/contributor-agreement-corporate.txt if work is as part one's daytime job)

The usual way to do this is to print out CLA, fill, sign, scan and send as email to info at fasterxml dot com.
If you could do this, we can retain the CLA (we just need one for any number of contributions for any Jackson projects), and then I can merge this fix immediately.

[dsw2127]

Just emailed my CLA

[cowtowncoder]

Received, merging. Thanks!