[Docker] Run Sliver server from writable CWD

[moloch--]

Describe the bug

Currently the Docker server process is run from a CWD that is not writable by the user the server process is executed as, which means that users must specify a --save location and by default builds will fail. Related to issue #130

Expected behavior

Default build commands should work with the need to specify additional flags.

Desktop (please complete the following information):

• OS: Docker/linux
• Version v0.0.7 (master)

[khast3x]

Hello,

Fixed the CWD issue by adding:

RUN chown -R sliver:sliver /go/src/github.com/bishopfox/sliver
USER sliver
ENTRYPOINT [ "/opt/sliver-server" ]

I have since managed to run the implant successfully 🎉

It might be more elegant to test writing perms before generating binary and output to /tmp or something? Idk.
In practical usage, running the C2 with docker is also done by mounting a volume so as to get the binary. Maybe use a default volume that is chowned correctly?

Cheers!

[moloch--]

There's a couple shortcomings of the current tests in that (1) they're execute as the root user, and (2) don't cover all use cases of thegenerate command. Changing the CWD is easy enough short-term but long-term I think we need to create better CI/CD integration tests.

[moloch--]

Fixed, but due to the increased code in the implant obfuscation process takes about 3 hours and 45mins on a t2.xlarge .... which is not ideal, but should be addressed once we have a better staged version.