Add a way to search by release date.

:phone::feet:

### Description

#### Overview

* Add optional search to releases pages by date.
* Add search partial/template.
* Tests for the above.
* Make pagination date-aware.

While this might be useful anyway as a standalone feature, it's actually the first step towards us being able to **export** a date range of releases. 

#### Backstory:

Right now every week we are asked by product for a list of features (inc. PRs, JIRA #s and Risks) we've released in Voice and we are forced to log all this info manually at the moment. 

However, all the data mentioned above is in Samson already associated with a list of releases, but we cannot 

1. list the specific releases in the date range or 
2. export it in some format (e.g. Confluence markdown) that product want. 

This PR addresses (1) and I'll create a followup PR to address (2) and export the date-range of releases in some format. 

#### UI changes (releases page for a project):

![screenshot_07_11_2014_22_27](https://cloud.githubusercontent.com/assets/527473/4961327/5b5139e6-66cd-11e4-8f6b-55530b6571c7.png)

/cc @steved555, @dasch, @jwswj, @halcyonCorsair, @princemaple, @bolddane, @pswadi-zendesk, @lukkry 

**PS**: Any idea why one of the builds is in error? 

### Steps to reproduce
Create a bunch of releases, adjust dates of some and ensure that date picker works and selects those in the correct ranges. 

### Risks
* None