Deployment now happens on Python 2.7.
Fixed sign bug.

Previously, the fast_* functions and all the is* functions would accept
'+' or '-' as valid numbers (treating them as '0'). This has been fix
so that they are correctly identified as invalid numbers.
Fixed 'nan' for safe_forceint.

Previously, safe_forceint returned a ValueError for 'nan', where the
intent was it would return the string 'nan' as-is.
Updated documentation and upped version.