[euscollada] Fix replace_xmls syntax in add_sensor_to_collada.py

[garaemon]

1. Force to use string. yaml parser automatically parse digit numbers as
integer or float. OTH, minidom parser always outputs everything in
string.
We force to convert yaml parser's output into string value.

2. Raise exception if there is no tag section.

3. Do not remove parent node if replaced_attribute_value syntax is used