Changes related to daytime scaling

### Summary of changes

 * splits our elasticsearch cluster across two availability zones (for better redundancy)
 * splits our elasticsearch cluster across "daytime" and "fulltime" nodes (for potential elasticity and scaling)
 * add a `logsearch` elasticsearch node attribute to be used for replica allocations
 * better support elasticsearch mode by auto-scaling group (master vs data vs client vs any)
 * disable master capabilities on the auto-scaling data nodes; only the frontend can now be the master
 * update `rake deploy_aws_cloudformation_stack` to require the service name instead of hard-coding it in configs
 * add `aws-cloudformation-cluster-resize` script for potentially scaling daytime nodes
 * bugfix, improve fabric file to respect Environment/Service/Name tags


### `./bin/aws-cloudformation-cluster-resize`

The script currently works in terms of scaling up/down, but it's not active in a cron job or anything. I'll add more discussion notes on our Tuesday issue. This script has an invocation which looks like:

    aws-cloudformation-cluster-resize {stack-resource} {parameter-key} {new-parameter-value} {es-attr} {replicas}

For example, the following invocation...

    ./bin/aws-cloudformation-cluster-resize ElasticsearchDaytimeGroup GroupDesiredCapacity 2 daytime_elastic 2

Will do the following...

 * lookup the `ElasticsearchDaytimeGroup` stack (based on the `environment` and `service` info)
 * compare the stack's current `GroupDesiredCapacity` parameter to know whether it'll be scaling up or down to reach `2` nodes
 * it'll query the cluster to lookup the running nodes (using the `logsearch` elasticsearch node attribute to figure out if `daytime_elastic` nodes are coming or going)
 * then it'll use the second `2` to update the cluster to indicate there should be two replicas of every shard (one for each AZ and one on the daytime nodes)

And the output and details look like...

    2014-02-03T22:08:32 + validating cloudformation references...
    2014-02-03T22:08:34 > RootStack: dev-logsearch-dpb587-test1 (2014-02-04T01:09:29.876Z)
    2014-02-03T22:08:35 > Target: arn:aws:cloudformation:eu-west-1:123456789012:stack/dev-logsearch-dpb587-test1-ElasticsearchDaytimeGroup-0EA284E003BA/15f91154-1460-4d2c-82bd-ceefec5065a1
    2014-02-03T22:08:38 > GroupDesiredCapacity: 0
    2014-02-03T22:08:38 - validated cloudformation references
    2014-02-03T22:08:38 = we will be scaling up
    2014-02-03T22:08:39 + discovering nodes...
    2014-02-03T22:08:39 > node 8xjZzm88S_O33n_OXqYqFw (10.236.89.176) is active
    2014-02-03T22:08:39 > node UoskahN2T7uUtM993k_FCg (10.64.202.67) is active
    2014-02-03T22:08:39 - discovered nodes
    2014-02-03T22:08:39 + disabling allocations...
    2014-02-03T22:08:39 - disabled allocations
    2014-02-03T22:08:39 + updating replication requirements...
    2014-02-03T22:08:40 - updated replication requirements
    2014-02-03T22:08:40 + updating stack...
    2014-02-03T22:08:45 > {"StackId":"arn:aws:cloudformation:eu-west-1:123456789012:stack/dev-logsearch-dpb587-test1-ElasticsearchDaytimeGroup-0EA284E003BA/15f91154-1460-4d2c-82bd-ceefec5065a1"}
    2014-02-03T22:08:45 - updated stack
    2014-02-03T22:08:45 + nodes are not yet ready...
    2014-02-03T22:14:46 > node DZII4pCsRvq6BTvFSA65Mg (10.236.87.214) joined the cluster
    2014-02-03T22:15:30 > node F48yg2soQJuX7TBCnh72fA (10.236.254.221) joined the cluster
    2014-02-03T22:15:30 - nodes are ready
    2014-02-03T22:15:30 + enabling allocations...
    2014-02-03T22:15:33 - enabled allocations
    2014-02-03T22:15:33 + cluster is not yet "green"...
    2014-02-03T22:17:49 - cluster is 'green'

When scaling down...

    $ ./bin/aws-cloudformation-cluster-resize ElasticsearchDaytimeGroup GroupDesiredCapacity 0 daytime_elastic 1
    2014-02-03T22:31:36 + validating cloudformation references...
    2014-02-03T22:31:38 > RootStack: dev-logsearch-dpb587-test1 (2014-02-04T01:09:29.876Z)
    2014-02-03T22:31:40 > Target: arn:aws:cloudformation:eu-west-1:123456789012:stack/dev-logsearch-dpb587-test1-ElasticsearchDaytimeGroup-0EA284E003BA/15f91154-1460-4d2c-82bd-ceefec5065a1
    2014-02-03T22:31:43 > GroupDesiredCapacity: 2
    2014-02-03T22:31:43 - validated cloudformation references
    2014-02-03T22:31:43 = we will be scaling down
    2014-02-03T22:31:44 + discovering nodes...
    2014-02-03T22:31:44 > node 8xjZzm88S_O33n_OXqYqFw (10.236.89.176) is active
    2014-02-03T22:31:44 > node UoskahN2T7uUtM993k_FCg (10.64.202.67) is active
    2014-02-03T22:31:44 > node DZII4pCsRvq6BTvFSA65Mg (10.236.87.214) will be terminated
    2014-02-03T22:31:44 > node F48yg2soQJuX7TBCnh72fA (10.236.254.221) will be terminated
    2014-02-03T22:31:44 - discovered nodes
    2014-02-03T22:31:44 + reviewing allocations...
    2014-02-03T22:31:45 - reviewed allocations
    2014-02-03T22:31:45 + disabling allocations...
    2014-02-03T22:31:45 - disabled allocations
    2014-02-03T22:31:45 + updating stack...
    2014-02-03T22:31:48 > {"StackId":"arn:aws:cloudformation:eu-west-1:123456789012:stack/dev-logsearch-dpb587-test1-ElasticsearchDaytimeGroup-0EA284E003BA/15f91154-1460-4d2c-82bd-ceefec5065a1"}
    2014-02-03T22:31:48 - updated stack
    2014-02-03T22:31:48 + nodes are not yet ready...
    2014-02-03T22:32:23 > node DZII4pCsRvq6BTvFSA65Mg (10.236.87.214) left the cluster
    2014-02-03T22:32:34 > node F48yg2soQJuX7TBCnh72fA (10.236.254.221) left the cluster
    2014-02-03T22:32:34 - nodes are ready
    2014-02-03T22:32:34 + updating replication requirements...
    2014-02-03T22:32:37 - updated replication requirements
    2014-02-03T22:32:37 + enabling allocations...
    2014-02-03T22:32:38 - enabled allocations
    2014-02-03T22:32:38 + cluster is not yet 'green'...
    2014-02-03T22:32:59 + cluster is 'green'