Bump version to 1.17.0

[appleby]

Additions and improvements

• Adds an interactive debugger to QVM, which can be entered by passing the -D command line flag (@jmbr, #245)

Misc

• The qvm binary is now installed in the Docker image (@notmgsk, #248)
• Retry with backoff when waiting for a given state in app-ng tests (@appleby, #249)