Release 0.1.2

Add history implementation

 * Add API/docstring
 * Improve predicate matching
Release 0.1.3

Add inst/timestamp to 'save!/'update! implementation
Release 0.1.4

 * Transactions implemented. Can wrap transactions around arbitrary
   blocks of code. Can also be tagged with metadata, and looked up from
   saved maps/records.
 * Improve find implementation and predicate specification
 * Add Travis-CI config & icon
Release 0.1.5
Release 0.1.6
Implement soft delete
Merge branch 'dev'
Release 0.1.7
Bump to 0.1.8-SNAPSHOT