add missing error message to line_extension in RESTAPI
add request for fetching line associated to an extension in RESTAPI
Merge branch 'get_extension_line' into 5003_restapi_incalls
write documentation for new line_extension association service in RESTAPI
rewrite REST API warning as a list of unstable services
write small description of extension resource in REST API
fix resource links in examples
fix error messages for line-extension service in RESTAPI
add small explanation about different context types
Merge branch '5003_restapi_incalls'