2020-06-30 v0.2.0

• Integrate new components shim-rune and runectl.
• Implement Enclave Runtime PAL API v2.
• Change to load the Enclave Runtime PAL on host side.
• Refresh skeleton example with enclave call ABI.

Please refer to this guide for the details about how to use this binary release. This release is validated with Occulm 0.13.0 for CentOS 7.5.