add non-prefixed border-radius property
add non-prefixed box-shadow property
add non prefixed linear-gradient function
remove vendor prefixes for border-radius
remove vendor prefixes for box-shadow
remove mozilla vendor prefix for linear-gradient
[ci skip] added link for trello board
Update excon dependency to version 0.21.0
Merge pull request #560 from delba/css

Add non prefixed CSS3 properties
Merge pull request #562 from westonplatter/master

[ci skip] added link for trello board
Move rvm downgrade to before_install
Update multi_json dependency to version 1.7.3
Update shoulda dependency to version 3.5.0
Update dalli dependency to version 2.6.3
Update net-sftp dependency to version 2.1.2
Update cucumber dependency to version 1.3.1
Update tilt dependency to version 1.4.1
Update fog dependency to version 1.11.1
Update newrelic_rpm dependency to version 3.6.2.96
Update pry dependency to version 0.9.12.2