Remove stringToEndpoint() variant that takes two parameters

[WAvdBeek]

Comments from MR 114:
"With oc_endpoint_string_parse_path exposed to Java we are
able to update the OCEndpointUtil.stringToEndpoint method so
it can take only one parameter. Since developers are already
using the stringToEndpoint method that takes two parameters
we need to still provide that method."
The only implementation I know that does this is OTGC, which we can have changed in an
upcoming release.

added android label

cc: @ljsachs

created merge request !121 to address this issue

based on branch:https://github.com/iotivity/iotivity-lite/tree/154-remove-stringtoendpoint-variant-that-takes-two-parameters