Retry logic on exception from Blockstorage

* Added timeout only for 507 case
* Fixing PEP8 typo
* Fixing last comment from review adding config timeout
* Fixing another round of comments - changing interval type and removing one parentheses

Change-Id: I7dbb51e5651383f7ba1ec6db294dda3eb427f760
Merge "Retry logic on exception from Blockstorage"