falsy params support

[dzubitskyi]

To have capability to update a Thunder properties with any falsy https://developer.mozilla.org/en-US/docs/Glossary/Falsy values, the current makeBody functionality needs to be improved.

Expected test suite

https://github.com/rdkcentral/ThunderJS/blob/master/tests/thunderJS.calls.spec.js

test('thunderJS - calls - argument based - empty string as an argument', assert => {
  resetStubsAndSpies()

  let thunderJS = ThunderJS(options)

  thunderJS.call('WebKitBrowser', 'userscripts', '')

  assert.ok(
    makeBodySpy.returned(
      sinon.match({
        jsonrpc: '2.0',
        id: 1,
        method: 'WebKitBrowser.1.userscripts',
        params: '',
      })
    ),
    'Should make a jsonrpc body and method WebKitBrowser.1.userscripts and params'
  )

  assert.end()
})

[nunofaria]

@dzubitskyi I have a branch on my fork that attempts to address this issue - https://github.com/nunofaria/ThunderJS/tree/36-falsy-param-support - feel free to comment on the fix attempt, thanks