Upgrade to Vert.x 3.5 to use RxJava2

[tsegismont]

Fixes #28

[tsegismont]

Do not merge yet!

@galderz @karesti sharing the code changes so that you can get an idea.

Still needs to be done:

• use the new reconnection param in eventbus js client
• check the solution profile works
• update the workshop steps

[galderz]

Looks good @tsegismont