Move the Gson object into the configurable properties

Change-Id: I85efa26b3268f4f1b595fafb3fa6e65c0eed2b65
simplify/future-proof DiskLruCache usage

Change-Id: I16f7e859a34fd4d5de2d3b978687499277883f9a
Merge branch 'master' of https://github.com/koush/ion

# By Koushik Dutta
# Via Koushik Dutta
* 'master' of https://github.com/koush/ion:
  simplify/future-proof DiskLruCache usage
  Move the Gson object into the configurable properties