Limit the checks for block device becoming available.

Instead of previously looping potentially forever for a block
device mapping to become created from the volume api, basically
blocking a greenthread until this happens we now will have a number
of attempts (defaulting to 10) that we will wait for the volume api
to create said block device mapping (or error out).

Fixes bug 1162064

Change-Id: I6ff0b42aad48df735d09f91a0a9fe98e6abcf2eb
Merge "Limit the checks for block device becoming available."