Handles unlimited range numbers

WTForms uses -1 to denote not min/max value. This makes the range and rangelength
validators incorrect. This patch falls back to min/max and minlength/maxlength
validation when one of the range values is -1.
Revert "Handles unlimited range numbers"

This reverts commit 5ef767c4e11a795a33739619a6b6dbd21c59d90a.
Handles unlimited rangelength values

WTForms uses -1 to denote no minlength/maxlength value. This makes the rangelength
validators incorrect. This patch falls back to minlength/maxlength
validation when one of the length values is -1.
Merge pull request #4 from DiscoveryHorizon/master

Handles unlimited range numbers