Updated gem installation directory from system to project-local

This commit makes it so that gem installation is done within the project
folder as opposed to a system-wide installation.

Signed-off-by: Byron Sanchez <byron@hackbytes.com>
Updated travis.yml

- Added cache directories for dependencies
- Updated installation so that it runs all necessary dependency setup.
  Scripts should be used for post-installation operations.

Signed-off-by: Byron Sanchez <byron@hackbytes.com>