Registry 0.8.0 RC1 Release

This release includes the following:

• ISSUE 568 : Synchronize Kerberos ticket renewal for non-renewable ticket
• ISSUE 582 : Using OpenJDK intstead of OracleJDK for Travis builds
• ISSUE-575: Add migration to enable editing of schema post upgrade to 0.7
• ISSUE 574 : Fix the issue while re-creating a deleted schema
• ISSUE:569: Support Kerberos credentials based Basic Authentication
• ISSUE 560 : Close unclosed ResultSet in storage
• MINOR : Update nexus url
• ISSUE 555 : Expose an option to disable canonical check while adding a new schema version
• MINOR : Updated README.md
• MINOR : Doc for running schema registry behind a load balancer