Connection error handling and automatic reconnection

Hi Paulo,
I'm enthusiastic about your redis mod. I am developing https://github.com/lbovet/vertx-redisques and https://github.com/lbovet/vertx-rest-storage which persist data in redis. Both modules are currently compatible with https://github.com/thmarx/vert.x-busmod-redis and mod-redis-io. Once this latter will be "released", I will recommend it as defaut choice.

In this PR, I added a fault tolerance mechanism that 1) issues an error reply in case of connection problem to all queued replyhandlers, 2) tries to reconnect when a new command is sent. I also adapted the pom/.gitignore to work with eclipse seamlessly.
Cheers,
Laurent