[HTTPS-E Rulesets] Bandcamp: some improvements

[Christopher Liu]

To whom it may concern:

It appears that the following has recently changed about Bandcamp:
- f0.bcbits.com now works as-is (as does s0.bcbits.com)
- Artist subdomains are no longer mismatched

However, once we start rewriting arbitrary subdomains, the following
exclusions may be necessary to make streaming content work:
<exclusion pattern="^http://(?:blog|popplers\d)\." />
<exclusion pattern="^http://(?:[\w-]+\.)?b(?:andcamp|cbits)\.com/crossdomain\.xml$"
/>
For the first of these, at least popplers5 exists. As for
crossdomain.xml, I'm not absolutely sure whether all cases need to be
excluded (since streaming seems to use HTML5 media when possible,
anyway).

C. Liu