[core-workflow] travis bottleneck at sprints

[Eric Snow]

tl;dr  Could we temporarily bump our cap on concurrent travis builds
during sprints?

During the sprints at PyCon we've been running into a serious
bottleneck with travis.  Having an extra allowance for builds already
is great, but during sprints even that gets swamped.  I am not sure
what projects contribute most to the problem, but I'm pretty sure it
isn't CPython (essentially 2 builds per PR).  Regardless, with the new
workflow this bottleneck significantly impacts the higher pace that
usually takes place at sprints.  Would it make sense to see if the
Travis folks would be willing to bump our limit temporarily during
each sprint?

-eric