Add support for kibana 5.6.x

[Granluc]

Hi,

I'm trying to install your plugin on kibana 5.6.2.
I have change the version in the package.json file.
But, I have an error on my browser, something lihe that:

Error: TypeError: _modules2.default is undefined

I have already seen this problem with an other. There are some change with version 5.6.x

Can you make an upgrade please?

regards,
Luc