New scripts to plot Qualimap and snpEff results

These are for the new IGN sample report and replace the defaults from qualimap:

### Default Coverage Histogram
![genome_coverage_0to50_histogram](https://cloud.githubusercontent.com/assets/465550/5048765/2eb1f170-6c20-11e4-98dc-af7a44543075.png)

### New Coverage Histogram
![cov](https://raw.githubusercontent.com/ewels/visualizations/master/examples/qualimap_coverage.png)

### Default Insert Length Histogram
![genome_insert_size_histogram](https://cloud.githubusercontent.com/assets/465550/5048768/331939b2-6c20-11e4-96c9-6ce2a8822216.png)

### New Insert Length Histogram
![insert](https://raw.githubusercontent.com/ewels/visualizations/master/examples/qualimap_insertsize.png)
I think `int` just drops the fractional part (rounds down)