Rename "install" to "install_venv" (#6)

This script conflicts with the linux tool "install" which is used
at least by preflight. Since this script isn't even used by
anything as far as the build system goes rename it to "install_venv"

ament_virtualenv/setup.py

@@ -35,7 +35,7 @@
             'build_venv = ament_virtualenv.build_venv:main',
             'combine_requirements = ament_virtualenv.combine_requirements:main',
             'glob_requirements = ament_virtualenv.glob_requirements:main',
-            'install = ament_virtualenv.install:main',
+            'install_venv = ament_virtualenv.install:main',
             'wrap_module = ament_virtualenv.wrap_module:main',
             'wrap_package = ament_virtualenv.wrap_package:main',
         ],