Also update godeps

s3gof3r was updated to determine the region based on the domain it was instantiated with in .New().
We have always set this to "", however the new change made this become "us-east-1" by default.

This commit:

- updates the s3gof3r instantiation logic
- adds a new Region attribute to the Config struct, which can then be utilized
for instantiating other S3 handlers (goamz or s3gof3r)

Fixes #91

- Retry getFile() upto `MaxGetFileAttempts` attempts

I have personally only seen the random 500 errors on pulls - if it turns out
that pushes are affected as well, we can apply similar logic to that as well.

In addition, this is a bandaid fix until we move towards the official aws go sdk.

This PR contains the following changes:

- Docker host health checking prior to pulls (seeking status code 200 on host:port/version GET
- Ability to disable host health checking via -disable-checks CLI flag
- Refactored dogestry server check code to work for both docker and dogestry endpoints
- Adapted ParseHostnames -> ParseHosts to return a host->port map (map[string]int)

Fixes #94

@talpert @intjonathan @idleyoungman

fixed region issue

Adds retry logic to the getFile() method

This PR contains the following changes:

- Docker host health checking prior to pulls (seeking status code 200 on host:port/version GET
- Ability to disable host health checking via -disable-checks CLI flag
- Refactored dogestry server check code to work for both docker and dogestry endpoints
- Adapted ParseHostnames -> ParseHosts to return a host->port map (map[string]int)

Fixes #94

@talpert @intjonathan @idleyoungman

…stry into dselans/docker_alive_check

Dselans/docker alive check