Injects environment variables into the app through webpack, rather than
script snippets in index.html.
As part of this:
* Updated server.js to use node’s path package to resolve file paths
* Ensure that all url environment variables passed to the app don’t
have a trailing slash, allowing for cleaner template urls
**Note**: There are still a number of constants that should be taken
out of the app and put into environment variables.
ReactS3FineUploader used to check the current url’s query params to
determine which method it should use to upload, but this decision means
the component is tightly coupled with react-router and history.js. A
major pain point is having to propagate the location prop all the way
down to this component even when it’s not necessary.
Now, ReactS3FineUploader’s parent elements can either parse the current
query params themselves or, if they have a location from react-router,
simply use the location.
Added a few utils to help parse url params.
