Batch processing and config file support

Added a config file to describe multiple jobs to run, and to provide
values for options not specified on command line.
In the config file, presets can be used to save duplication of rip
options common to multiple jobs.

config.yml

@@ -0,0 +1,40 @@
+---
+options:
+    verbose:      1
+    log_file:     /tmp/handbrake-cluster-client.log
+    job_servers:
+      - build0.example.com
+      - build1.example.com
+    report_email: me@example.com
+  
+presets:
+  tvseries:
+    nice:            15
+    format:          mkv
+    video_codec:     x264
+    video_width:     720
+    video_height:    480
+    quantizer:       0.61
+    deinterlace:     2
+    audio_tracks:    1
+    audio_codec:     ac3
+    audio_names:     English
+    subtitle_tracks: 1,5
+  disk1:
+    input_filename: /dev/sr1
+  disk2:
+    input_filename: /tmp/dvds/disk2/VIDEO_TS
+
+jobs:
+  - presets:
+      - tvseries
+      - disk1
+    output_filename: /tmp/title1.mkv
+    title:           1
+
+  - presets:
+      - tvseries
+      - disk2
+    output_filename: /tmp/title2.mkv
+    title:           -1
+