Boolean string values are not converted correctly

Boolean values must be written as string in the configuration file, e.g.

RGW_API_SSL_VERIFY="True"
RGW_API_SSL_VERIFY="False"

The current implementation does not handle this correct, so "False" will be converted to True.

bool("True") => True
bool("False") => True
bool(0) => False
bool(1) => True