Proposal accept/reject for RFP managers

## Overview

As an authorized member of a team that created an RFP, view submitted proposals and accept/reject them.

## Acceptance criteria:
> * We need to enforce these pages are only visible and viewed to the team members
> * The API should enforce accepting or rejecting can only happen from team members

* The `require_request_for_proposal_manager` method of the `RequestForProposalAuthorization` module handles authentication for the `accept` and `reject` actions of `ProposalsController`
* Redirects through sign in if not logged in.
* Proposal submit form rendered if logged in and not authorized to view the proposals index.
    ![image](https://cloud.githubusercontent.com/assets/692632/3194886/c61f6a7e-ed04-11e3-8810-323b00380571.png)

> Do we want a bulk list view for proposals?
> Do we want people to accept / reject from the list view?
> What information is displayed in the list view?
> How does a user navigate from the list view to a specific item? Is it a modal popout, or a new page?

* Bulk list, you can accept/reject from list view.
* All information displayed in list view, but the bio is truncated.
* To show a single proposal, click the bio link to open a modal with the full bio.

## States

### 1. All proposals pending
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![image](https://cloud.githubusercontent.com/assets/692632/3182546/44018136-ec54-11e3-98ee-7268db127e27.png)

### 2. Proposal pending acceptance
**Note:** I changed the text to "Accepted, pending checkout" per discussion with @juliangiuca

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![image](https://cloud.githubusercontent.com/assets/692632/3182538/254ef4a8-ec54-11e3-9687-37ad1c16cdef.png)

### 3. Proposal accepted
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![image](https://cloud.githubusercontent.com/assets/692632/3182553/757e8344-ec54-11e3-8527-9e72ff99d8af.png)