Sync oslo imageutils, strutils to Nova

Changes in imageutils:
===============================
b455fac Enable decimal value input in imageutils.QemuImgInfo
bec3a5e Implements SI/IEC unit system conversion to bytes
8b2b0b7 Use hacking import_exceptions for gettextutils._
aad179d Fixing misspelled encryption key in QemuImgInfo
12bcdb7 Remove vim header
2bd46eb Refactors byte size extraction logic

Changes in strutils:
====================
bec3a5e Implements SI/IEC unit system conversion to bytes
e53fe85 strutils bool_from_string, allow specified default
8b2b0b7 Use hacking import_exceptions for gettextutils._
84d461e Fix a bug in safe_encode where it returns a bytes object in py3
12bcdb7 Remove vim header
3970d46 Fix typos in oslo
1a2df89 Enable H302 hacking check
67bd769 python3: Fix traceback while running python3.
b0c51ec Refactors to_bytes

Change-Id: I3e887756af37823dc6486d1496222825ddc20f0c
Related-bug: #1189635
Related-bug: #1193765
Related-Bug: #1257829
Merge "Sync oslo imageutils, strutils to Nova"