minimalist-pcproxy: Makefile cleanup

minimalist-pcproxy: Makefile cleanup

- Fixed LICENSE
Software is licensed under MIT
- Added PKG_LICENSE_FILES

- The was wrong date in PKG_VERSION
The latest commit is 2014-12-12.

- Changed package versioning
Before: minimalist-pcproxy_2015-01-12-2d6d1b0b0a3b79a9b4a9b0a7606a84600a967bcb-2_arm_cortex-a9_vfpv3-d16.ipk
After: minimalist-pcproxy_2014-12-12-2d6d1b0b-1_arm_cortex-a9_vfpv3-d16.ipk

Also the downloaded tarball is smaller by 0,4 kB

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>