improve wiki dump script (#16)

This patch addresses:

* remove `cp` command of non existing folder `moin_static197`
* fix `cp` command for logo.png
* make regex to convert `custom` links from `abs` to `rel` more specific in order to not overmatch
* rewrite remaining `moin_static197` links
* add `jquery` to all pages (since other js files depend on it)

@tfoote Please review.