1.0.7

• Reorg the dockerfile for better cache-ability. system-test, #31.
• soroban-rpc: do not wait for Horizon since it does no longer depend on it. system-test, #36.
• local source path for git refs and/or image overrides during build. system-test, #37.
• Update system tests for new contract invoke. system-test, #38.
• Added Auth Next Scenario Test. system-test, #34.