Remove unnecessary entrypoint.sh +x permission, fix Windows build

[dagood]

I've made some changes to fix a couple issues I ran into when building the Dockerfile on Windows, with what I'd consider a pretty typical dev configuration:

• Windows filesystems don't preserve permissions, so re-apply script execute permission in the Dockerfile.
• Git autocrlf is typically enabled on Windows, so add a .gitattributes to make sure scripts like entrypoint.sh are cloned with LF.

Also, I removed +x permission from the copy of entrypoint.sh in the repository. It doesn't seem like this script is useful to run on a dev machine, only looks to be useful inside the container, and now that the execute permission is applied by the Dockerfile, it's not necessary to mark it as executable in the Git repository.

[pranavgaikwad]

@dagood Thank you for taking the time to fix this!