Set license files and headers for bitcoin.org's content
Dev Docs: Link To CC-BY License For Covered Code

A code snippet from the wiki was correctly attributed to its author, but
I didn't realize I also had to link to the license.  Corrected.
Dev Docs: Describe Filterload Message (Final P2P Message To Document)

New material:

* Add documentation for `filterload` message to devref. This is the last
  P2P protocol message which needed documentation.

* Add an example for creating a bloom filter to the devex, as well as an
  example of checking data against that filter.

Edits:

* Change "object" to "element" in previous `filteradd` text. I decided
  "transaction element" made more sense than the more generic "object".
  Text should be fully consistent across both `filterload` and
  `filteradd` descriptions.

* Mentioned that I think the example hexdump in the `alert` section is
  public domain. (Only the hex is taken from the wiki; the annotation is
  my own work.)
Dev Docs: Made Corrections To Filterload Docs Suggested By @saivann (Thanks!)
Merge branch 'license'
Add Luigigiuseppe Prosperi to the list of contributors
Add missing redirection
Update zh_TW translations
Merge Pull #657: Dev Docs: Describe Filterload Message (Final P2P Message To Document)
Dev Docs: Document Headers-First (And, By Extension, Blocks-First)

This commit provides a detailed overview of 0.10's headers-first block
download method and significantly improves our current documentation of
the current block download method, which I've called retroactively named
blocks-first for parallelism.

New And Significantly Revised:

* New Initial Block Download (IBD) section (h3) with separate
  Blocks-First and Headers-First subsections (h4) using parallel
  composition.

* 100% rewritten Blocks Broadcasting subsection describing in
  blocks-first relay in much more detail, plus new descriptions of
  headers-first relay and SPV downloading.

* New Orphan Block subsection (under Blocks Broadcasting) describing
  orphan blocks and how they're handled differently under blocks-first
  and headers-first. Also includes a simple illustration of the
  difference between orphan blocks and stale blocks. Thanks to @luke-jr
  for his s/orphan block/stale block/ commit a couple months ago---that
  made this commit much easier.

Edits:

* Cleaned up a couple cases missed by previous s/orphan/stale/ commit
  because they used past tense (orphaned).

* Mentioned direct RPC changes introduced by headers-first pull in the
  RPC docs. TODO'd those sections to ensure we provide updated examples
  once 0.10 is released.

* In P2P reference section, mentioned that a `block` message can be sent
  unsolicited by miners.

* Mention that `getheaders` and `headers` were added in protocol
  version 31800.

* Moved a few internal links around and added a few new internal links.

Administrivia:

* Started adding "TODOv0.10" in HTML comments to places that need to be
  updated when 0.10 is released so that I can easily git grep for that
  tag later.