adding 'aliases' - 'poi' & 'admin' for the layers param.
adding type
adding type only if clean.layers are not undefined
Merge pull request #30 from pelias/alias_layers

adding 'aliases' - 'poi' & 'admin' for the layers param.
Merge pull request #31 from pelias/search-layers

searching layers
Merge branch 'master' into multiple_suggesters