This patch makes the python tests source-compatible with python 3, while
leaving the interpreter at python 2 for now.
The tradeoff is that this source is no longer compatible with python
versions < 2.6, and requires gobject-introspection for the glib-based
tests.
According to HTS 1.0 (Table 3.1, and Sections 3.1.1.4 and 3.2), the
Temperature Type Characteristic is optional. The only restriction is
that it shall not be present if the Temperature Type is non-static, for
which case the "Temperature Type" field shall be present on the
Temperature Measurement Characteristic value.
Given there is no default value specified when the Temperature Type is
static and unknown, the "Type" entry for MeasurementReceived() on the
Thermometer API was made optional.
