'Initialize a UrlTemplate provider with layer and template string.
http://docs.python.org/library/string.html#template-strings'

def __init__(self, layer, template, referer=None, source_projection=None, timeout=None):

    self.layer = layer
    self.template = Template(template)
    self.referer = referer
    self.source_projection = source_projection
    self.timeout = timeout
