Makefile: update make targets

Primary method of launching is now 'make studio'.

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Merge branch 'develop' of github.com:kemitix/docker-android-studio into develop
Makefile: studio - runs in X over local unix socket

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Makefile: group TAG with other variables

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Makefile: run target uses variables

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Makefile: shell target uses variables

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Makefile: original target studio renamed to avoid name clash

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Makefile: target studio-ssh will always cleanup after itself

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
README.md: update documentation

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>