Detect initial loading of builder with hash ID

Detect the case when the user loads a story in the builder where the
builder ID is a hash argument.  In this case, the builder isn't properly
bootstrapped with story and section data.  Force a hard reload so the views
are properly bootstrapped.

Still to do is to properly generate the refresh URL in IE.

Addresses #417
Reload builder when story ID is in a hash

In IE9 (and presumably other browsers that don't support the History
API) Backbone falls back to using hashes to route to different views in
the application.  This however, causes a problem when reloading pages
because, without the ID in the URL, Django doesn't know to include the
JSON to bootstrap the Backbone views.

In the router, we detect this case, and force a reload of the page in
the browser (with the hash removed) to properly bootstrap the views.

Addresses #417
Integration test for #417

Test that the browser reloads the page when visiting a page with a hashed
story ID.

As part of this, I added some additional steps for clicking buttons to the
terrain module. I also updated the step for creating users to check if
a user already exists, allowing successive tests involving the same test
user to be run without clearing the database.
Don't create the connected story template in tests

Don't create the connected story template in integration tests since in
production, we're now just using the Photovoice template for connected
stories. It makes sense to replicate this behavior in tests.
Merge branch '417_reload_hash_url' of github.com:ghing/atlas into 417_reload_hash_url
Test for loading story with hashed workflow step
Don't refresh the browser on initial save

The build handler of the router now differentiates between the case
where the user is trying to save the story for the first time and where
they're trying to load an existing story.  In the former case, it's ok
to keep going as the story has already been bootstrapped by the
template. In the latter case, the browser should be reloaded with a
non-hashed story ID in the URL so the Django view can correctly
bootstrap the Backbone view.

Addresses #417
Support initial load with hased story ID and step

Support loading the story when there is both a hashed story ID and workflow
step in the URL.

Addresses #417
Added basic automated builder integrationt tests

Since the fix for #417 has the potential to break other things in the
builder routing, I wanted to make sure that there was a way to quickly and
consistently test this fix and other future fundamental changes to the
builder.
Add implementation of steps for builder tests

I forgot to add this file in the previous commit.
Workaround for #558

Adds a check for window.polyfills before calling
window.polyfills.placeholders(). While this doesn't allow the polyfills
to be properly loaded, it does keep the error from occuring.
Better logic for deciding when to reload

What was needed was not to check whether the story model had been
loaded, but instead to update the hasStory property when the story was
initially saved.

Addresses #417
Remove gradient from social login buttons in IE

The method for creating gradients in MSIE overflows the rounded corners
of the button and looks sort of weird. The most lightweight, easy
workaround is to remove the gradient effect in IE.

Re-closes #347.
Merge branch 'release' into develop
Merge branch '417_reload_hash_url' into develop