update build instructions

A couple of tweaks

adding a few more client and network metrics

Add slave offset metrics

Update glide.yaml

as we all know

Changes for exporting redis only metrics if needed

upgrade redigo to 1.1.0  for rediss://

[glide] Update sirupsen dependency to use new path to repo

Add replication metric

Reset keySizes and keyValues GaugeVec before scraping to remove old data

add binary to .gitignore

Make exporter able to connect via bindings on cloud foundry

Also provides better error handling and loggin. Removes unused methods.

Parameters via flags have priority, so the CF bindings are only
used if there are no addresses after evaluation of the flags and files
instead of localhost.