container: standard PATH location for the script

[marcaurele]

In order to simplify the execution in a shell (such as in CI systems), the executable should be located in a standard UNIX PATH location. I picked /usr/local/bin in order to specify the executable is not coming from a standard package.

• link /ecs-deploy to the new location for compatibility in case some people are already using the image with this location of the script.
• remove some RUN command as the files are already executable in git, therefore the copy during the build will keep those x flags.
• minor typo in comment

It might be issue faced by the user in #124.

Currently, this fails:

$ docker run -it --rm --entrypoint "" silintl/ecs-deploy:3.10.0 ecs-deploy --version
docker: Error response from daemon: OCI runtime create failed: container_linux.go:367: starting container process caused: exec: "ecs-deploy": executable file not found in $PATH: unknown.

With the change:

$ docker run -it --rm --entrypoint "" ecs-deploy:local ecs-deploy --version
3.10.0