Add support for installing assets to a file path.

[cardi]

Proposed fix for #24.

This would require a new asset_path in the STORAGE_BACKEND dict.

Example settings.py:

# fluffy-specific configuration options
# storage backend (how are the files stored after being uploaded?)
STORAGE_BACKEND = {
    'name': 'file',
    'object_path': 'tmp/object/{name}',
    'html_path': 'tmp/html/{name}',
    'asset_path': 'tmp/assets/{name}',
}

# branding
BRANDING = 'fluffy'
CUSTOM_FOOTER_HTML = None

# URL patterns
HOME_URL = 'http://localhost:5000/'
FILE_URL = 'http://localhost:4999/object/{name}'
HTML_URL = 'http://localhost:4999/html/{name}'

STATIC_ASSETS_URL = 'http://localhost:4999/assets/{name}'

# abuse contact email address
ABUSE_CONTACT = 'abuse@example.com'

# max upload size per request (in bytes)
MAX_UPLOAD_SIZE = 10 * 1048576  # 10 MB

# max size Flask will accept; maybe a little larger?
MAX_CONTENT_LENGTH = MAX_UPLOAD_SIZE * 10

and a diff with settings/dev_files.py:

diff --git i/settings/dev_files.py w/settings/dev_files.py
index 8fbe50d..8b080ab 100644
--- i/settings/dev_files.py
+++ w/settings/dev_files.py
@@ -4,6 +4,7 @@ STORAGE_BACKEND = {
     'name': 'file',
     'object_path': 'tmp/object/{name}',
     'html_path': 'tmp/html/{name}',
+    'asset_path': 'tmp/assets/{name}',
 }

 # branding
@@ -15,7 +16,7 @@ HOME_URL = 'http://localhost:5000/'
 FILE_URL = 'http://localhost:4999/object/{name}'
 HTML_URL = 'http://localhost:4999/html/{name}'

-STATIC_ASSETS_URL = 'http://localhost:5000/{name}'
+STATIC_ASSETS_URL = 'http://localhost:4999/assets/{name}'

 # abuse contact email address
 ABUSE_CONTACT = 'abuse@example.com'

I'm not sure if settings/dev_files.py should be updated, since the dev environment uses Flask to serve static assets. Perhaps it could go into a new settings/prod_files.py?