Improve searching

@ciberch now that I was giving a look at Bowtie because we need to show the VisitorAction records here, I saw the opportunity to improve the search feature a bit, this what I've added:

- Now is possible to search on specific fields, here are some examples with the text entered in the search box:

"first_name:Ruben" => Match all records that contains Ruben (case insensitive) in the first_name field.

"first_name:Ruben;invited:true" => Match all records that contains Ruben (case insensitive) in the first_name and are invited.

Additionally I've added the ability to search on Integer and Boolean field types. Search on all fields works normal as before, in this case it only applies the search over text fields.

cc/ @josecp