changed the method of determining architecture

Regular expression to determine the architecture can not be correctly
determined in the environment of non-US.

For example, it would look like this in the Japanese environment.

`wmic OS get OSArchitecture`

OSArchitecture
32 ビット

Therefore, it has been modified regular expression to determine only
numbers.
Merge pull request #13 from simpraight/master

Fail to detect the architecture in an environment of non-US