Fix recovery logic to work with etcd v0.1.1

* etcd guarantees that the list of machines will have the current leader first, so change the leader detection logic accordingly
* Remove Client#leader since it wouldn't reflect etcd's /v1/leader anyway (the docs for #machines has been changed to say that the leader is the first in the list)
Add http:// to ETCD_URI for the integration specs
Move dependencies to .gemspec
Version bump to v1.0.0.pre1