Removed unused and broken `one_for_one` shard
replacement.
Since there is now only one type of shard
replacement the atom that separated the old two
types is now redundant.
Added a shorthand to updating the single node, it
still uses the old functions but if the plan is to
stop using them this should be refactored to not
use rpc-style gen_server calls.
Created a escript that updates shards in a running
logplex node.
Removed the -s flag and added a -k flag to read
from the file. Also did a bit of refactoring to
be able to reuse more code.
Check for the `LOGPLEX_NODE_NAME` variable and 
connect to it rather then the local node if it is
set. This is mostly used for testing.
Added a CT test for the replace shard e-script.
Removed the fold over nodes from `logplex_shard`.
Merge pull request #46 from heroku/shard_update

Changes applied to the branch, so I'm merging it in to the master.