v0.3.1

Changes since v0.3.0:

• gps: Add satisfiability check for case variants (#1079)
• Validate Project Roots in manifest (#1116)
• gps: Properly separate sources for different gopkg.in versions & github
  (#1132)
• gps: Add persistent BoltDB cache (#1098)
• gps: Increase default subcommand timeout to 30s (#1087)
• Fix importer issue where the
  importer would drop the imported version of a project (#1100)
• Import analyzer now always uses the same name, fixing the lock mismatch
  immediately after dep init issue (#1099)
• Add support for importing from govend
  (#1040) and LK4D4/vndr (#978) based projects
• gps: gps no longer assumes that every git repo has a HEAD (#1053)
• os.Chmod failures on Windows due to long path length has been fixed (#925)
• Add version command (#996)
• Drop support for building with go1.7 (#714)
• gps: Parse abbreviated git revisions (#1027)
• gps: Parallelize writing dep tree (#1021)
• status now shows the progress in verbose mode (#1009, #1037)
• Fix empty Constraint and Version in status json output (#976)
• status table output now shows override constraints (#918)
• gps: Display warning message every 15 seconds when lockfile is busy (#958)
• gps: Hashing directory tree and tree verification (#959)
• ensure now has -vendor-only mode to populate vendor/ without updating
  Gopkg.lock (#954)
• Use fork of Masterminds/semver until
  Masterminds/semver issue#59
  is fixed upstream (#938)
• gps: Ensure packages are deducible before attempting to solve (#697)

Note that a number of these changes represent larger WIP - for example, the tree hashing, or the persistent boltdb cache: these will both be major boons to performance once complete, but the code integrated in those PRs is not in active use just yet.