OpenBLAS

TST: Azure manylinux1 & clean-up

* remove some of the steps & comments
from the original Azure yml template

* modify the trigger section to use
develop since OpenBLAS primarily uses
this branch; use the same batching
behavior as downstream projects NumPy/
SciPy

* remove Travis emulated ARMv6 gcc build
because this now happens in Azure

* use documented Ubuntu vmImage name for Azure
and add in a manylinux1 test run to the matrix

[skip appveyor]