Improve SSL Failure Error Message

While building Ottoman and testing it against SSL there were error messages thrown but was not meaningful and easy to debug.

1. Mandatory Client Certificate required but none provided: 

      `FATAL ERROR:
          libcouchbase experienced an unrecoverable error and terminates the program
          ...
         assertion failed in C:\Jenkins\workspace\nodejs\couchnode\couchnode-scripted-build-           pipeline\couchnode\deps\lcb\src\ssl\ssl_c.c at line 409`.

      2. trustedStorePath pointing to a wrong CA

       **       

         `Error: LCB_ERR_SSL_ERROR (1002): A generic error related to the SSL subsystem was             encountered. Enable logging to see more details ... code: 1002`

     3.  Mismatched client cert/key or invalid file path specified:

           **           

{{this._inst = new binding.Connection(
^

Error: LCB_ERR_SSL_ERROR (1002): A generic error related to the SSL subsystem was encountered. Enable logging to see more details
at new Connection (D:\code\ottoman-test\node_modules\couchbase\lib\connection.js:129:18)
at Cluster._getConn (D:\code\ottoman-test\node_modules\couchbase\lib\cluster.js:610:14)
at new Bucket (D:\code\ottoman-test\node_modules\couchbase\lib\bucket.js:20:26)
at Cluster.bucket (D:\code\ottoman-test\node_modules\couchbase\lib\cluster.js:482:12)
at Ottoman.connect (D:\code\ottoman-test\node_modules\ottoman\lib\ottoman\ottoman.js:134:41)
at Object.<anonymous> (D:\code\ottoman-test\index.js:16:28)
at Module._compile (internal/modules/cjs/loader.js:1138:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
at Module.load (internal/modules/cjs/loader.js:986:32)
at Function.Module._load (internal/modules/cjs/loader.js:879:14) {
code: 1002
}}}

{{}}

4.Wrong Client cert/key pair

{{}}
 {{FATAL ERROR:
libcouchbase experienced an unrecoverable error and terminates the program
to avoid undefined behavior.
The program should have generated a "corefile" which may used
to gather more information about the problem.
If your system doesn't create "corefiles" I can tell you that the
assertion failed in C:\Jenkins\workspace\nodejs\couchnode\couchnode-scripted-build-pipeline\couchnode\deps\lcb\src\ssl\ssl_c.c at line 409}}
{{}}

In all of the above cases a more appropriate and easy to debug error message would have been  :   "Invalid client certificate or client certificate not provided, more common reasons include certification path being invalid or certificate generated is invalid." 

This could very well be an issue with libcouchbase or with server, please raise an appropriate ticket and link it to this ticket.