Revert "Pull in patched eventlet to fix Second Simultaneous errors"

This reverts commit 0011e19c15cee09c21a1ec5f772a480a677201b9.

Eventlet version 0.15.1 has been released with the fix to the
"Second Simultaneous error"

Change-Id: I1e6e27f32f1b24e14a4ecb91f3433647fbb69a3e
Merge "Revert "Pull in patched eventlet to fix Second Simultaneous errors""