Use Search::Elasticsearch instead of Elasticsearch, adapt code and tests

Elasticsearch is deprecated since 2014-03-05, and Search::Elasticsearch
replaces it. There were also some API changes which required changes to
the code and tests.
Adapt pod to the change to Search::Elasticsearch
Rename 'servers' to 'nodes' for consistency with Search::Elasticsearch

Also add some code to the BUILDARGS wrapper which emits a warning and
copies the 'servers' parameter to the 'nodes' parameter to stay backwards
compatible (as long as nobody used the 'servers' accessor). As this affects
the model object construction, add a few tests for the configuration
handling, too.
Merge pull request #1 from mstock/feature/search-elasticsearch-migration

Use Search::Elasticsearch instead of deprecated Elasticsearch
Add empty line after package declaration

This avoids a warning emitted by newer versions of the PkgVersion plugin.
Add myself to author list

I bear the blame for some potentially breaking changes and bugs introduced
during the migration to Search::Elasticsearch, and this adds a hint to the
metadata about this.
Remove UploadToCPAN plugin

It's already part of Dist::Zilla::PluginBundle::Basic, which results in two
upload attempts to CPAN where the second one fails.
Add brackets around version in tag_regexp of ChangelogFromGit plugin

This avoids empty version strings in the generated Changes file.