Version 20170610 with hwaccel for rpi

Based on ccrisan's version 20170610, but with hwaccel for Raspberry Pi. More information about hwaccel here motioneye-project#365.
This is completely untested and highly experimental. Use at your own risk.

To get the optimum movie quality, tune the following:

• resolution
• fps
• movie quality

The below configuration is a good default:

• Resolution: 800 x 600
• fps: 20
• Movie format: H.264
• Movie quality: 75%
• Pre-cap: 1 (higher pre-cap uses more RAM)

Known issues / limitations:

• Raspberry Pi with 256MB RAM can only run up to 800 x 600 resolution due to limited RAM.
• 1920 x 1080 resolution records at 5 fps.
• 1280 x 720 resolution does NOT work.
• Wifi stops working after first boot when connecting to certain access points. Workaround here: motioneye-project#1012

Changes:

• Fixed fast movie playback issue.
• added gpu_stat script to monitor GPU usage.