First attempt at having plots laid out by gridspec.
Use fig.add_subplot instead of plt.subplot to turn off collision
checking.
Merge branch 'master' into gridspec_plots

Conflicts:
	EIYBrowse/tracks/interval.py
Use browser width to determine overlapping gene labels.
Set BED jittering a little lower.
Location labels should be left aligned so as not to overlap the adjacent
axis.
Give plots a little more horizontal space.
Merge branch 'gridspec_plots'
Merge branch 'master' of github.com:rbeagrie/EIYBrowse