Tigon SQL changed interface setup

Changed interface setup and added query rewriting to comply with Tigon SQL compiler expectations

* Now each defined schema has an associated interface named `"<schemaName>"` ~~+ "s"~~ defined in file `<hostname>.ifq`
* ~~Each interface definition has a new field `<SubStream>` in `ifres.xml`~~
* ~~The Tigon SQL queries are re-written, such that each occurrence of `" " +  "<schemaName>" + " "` is replaced by `" [" + "<schemaName>" + "]." + "<schemaName>" + " "` to create the corresponding gsql file.~~
* The user is now expected to specify the interface as well as the schema while writing a Tigon SQL query
Add a comment here saying : For now interface set names are same as the Schema names (one-to-one mapping)