Fix UTF-8 encoding for JSON. refs #1292.
JSON import fixes:
Protect against malloc returning NULL, picked up by Coverity.  refs #1293.
Resolve lint issues.  refs #1294.
Resolve lint issues related to JSON import.  refs #1294.
Merge pull request #1298 from wiredtiger/json-load-lint

Lint, Coverity fixes: #1292, #1293, #1294.