Add istanbul config file
Add istanbul config file

Since the hfc/hfc-cop split, the repository now hosts two
packages, and as a result we had to use some npm package technique
such that the test cases can be left in one place and drive
testing of both source roots. A side effect is that code coverage
with istanbul now must be specially configured to understand what
is the root of the source tree (it won't be "." any longer but
under node_modules/hfc and node_modules/hfc-cop)

istanbul does not support multiple roots, so we can only tell it
to instrument either hfc or hfc-cop. Since majority of the code
is in hfc, we'll have to settle with using that only.

Change-Id: I4a528c10ef5b8a9e0f3202fb676ae6e3a1da5be1
Signed-off-by: Jim Zhang <6775950e159d0bc2e58935ca2201ba88526dddf0@us.ibm.com>

ratnakar-asara/fabric-sdk-node,ratnakar-asara/fabric-sdk-node,ratnakar-asara/fabric-sdk-node,ratnakar-asara/fabric-sdk-node,adityachap/fabric-sdk-node,adityachap/fabric-sdk-node