1.6.0 rc1

Changes since v1.6.0-beta1:

ezplatform changes

• pin selenium docker image version to 2.53.1 (#141)
• Misc README updates (#139, #140)

ezsystems packages updates

Package	Version
ezsystems/ezpublish-kernel	v6.6.0-rc1
ezsystems/ez-support-tools	v0.1.1-rc1
ezsystems/platform-ui-bundle	v1.6.0-rc1
ezsystems/ezplatform-solr-search-engine	v1.1.2-rc1

Third party packages updates

Package	Version change
paragonie/random_compat	v2.0.2...v2.0.3
league/flysystem	v1.0.28...v1.0.32