Added testing coverage mandate to travis testing.
Missed the cover flag.
Reduced coverage target to consider batch code being skipped with version 1 of protocol.
Updated .travis.yaml to match build lifecycle description on travis' site.
Added go get.
Merge pull request #249 from phillipCouto/force_cover_target

Added testing coverage mandate to travis testing.
Added note about test coverage in the contribution guidelines
Corrected supported versions
Add MapScanCAS() to capture a prev row safety.
Remove an unnecessary if branch.
Refactor Scan/ScanCAS/MapScanCAS common logics
Add comment the motivation of MapScanCAS()
Merge pull request #250 from matope/MapScanCAS

Add MapScanCAS() to capture a prev row safety.
Pass a map with refs to store columns to MapScan()