Fix `utils.copy` for copying files, add unit tests

`copy('', 'a/b.ext0', 'c/d.ext1')` is copying `a/b.ext0` into `c/d.ext1/b.ext0`
(creating folder `c/d.ext1` in the process) instead of `c/d.ext1`.
Bug introduced by e03cf3f51735d5387fee7064cae89aaa1d34a0a6.
Simplify usage of `utils.copy`

Remove confusing parameters, clarify usage in __doc__
`ctrl+c` now correctly terminates `fab serve`

Previously `ctrl+c` a `fab serve` wouldn't necessarily terminate the web server. Even if it does, re-using the command `fab serve` might result in the following error:

```
socket.error: [Errno 48] Address already in use
```

This fix manually creates a `TCPServer` with `allow_reuse_address` set to `True`, which solves this issue.

Tested on OS X 10.9.1.
Update settings.rst to match tag cloud code

According to the implementation, the value of `tag.1` should be between 1 and `TAG_CLOUD_STEPS`, inclusive.

See:
https://github.com/getpelican/pelican/blob/master/pelican/generators.py#L457
Extra functionality for pelican-import for wordpress imports
Merge pull request #1234 from alistairmagee/wp-custom-posts-and-attachment-download

WordPress custom posts and attachment download
Merge pull request #1202 from tomtung/patch-2

Update settings.rst to match tag cloud code
Merge pull request #1200 from tomtung/patch-1

`ctrl+c` correctly terminates&reenables `fab serve`
Merge pull request #1183 from Rogdham/pelican-fixcopy

Fix `utils.copy` for copying files
add signal article_generator_pretaxonomy

invoked before categories and tags lists are created
useful when e.g. modifying the list of articles to be generated
so that removed articles are not leaked in categories or tags