Refactor Duration

- Initialize suffixes at one shot
- Delegate whitespace handling to the regex
- Remove redundant checking on time unit type from the regex
- Derive count and unit from the regex matching result
Refactor Size

- Initialize suffixes at one shot
- Delegate whitespace handling to the regex
- Remove redundant checking on size unit type from the regex
- Derive count and unit from the regex matching result
Merge pull request #569 from arteam/refactor_utils

Refactor Duration and Size a bit