Reporting REST interfaces must also report string representation

[whantana]

REST interfaces such as /html, /tabdelimited/, & JSON must report back the string reading format if necessary.

Consider a tabdelimited version with 3 cases :

Node/Capability with only double readings -> the already implemented version
Node/Capability with only string readings -> the second column contains the string reading
Node/Capability with both double and string readings -> adding a third columnt containg the string reading.