[picoFeed]: Add support for CP1255 encoding

fixes encoding errors reported in fguillot/miniflux#266
[picoFeed]: forward the target of a redirection to the grabber

The website 01net.com uses feedsportal.com to deliver there feeds. The article
URL within the feeds points to feedsportal.com and is HTTP 301 forwarded to
01net.com. As the content grabber does not get notified about this forwarding
and the expected rule file is still feedsportal.com.php. That isn't s.th. the
user expects and it could be impossible to write content grabber rules for
different websites using feedsportal.com.

This was reported in fguillot/miniflux#267
[picoFeed]: fix stripHeadTags with optional HTML4 attribute profile

The head Tag could have an attribute profile, so a more dynamic compare is
needed. As preg_replace needs a proper encoded document, do the utf-8 encoding
before stripping the head tag.

Spotted while using the content grabber with 01net.com which results in double
encoded é's.
Move update icon and update icon blinking to css

Use CSS3 Animation for the "loading icon" blinking and move the definition of
the loading icon to CSS as well.

CSS3 Animations are supported by IE10, Firefox and using the -webkit prefix by
Chrome and Safari.

I've dropped the usage of element.classList in favour of supporting refreshing/
article downloading in IE9 (again). The classList stuff isn't necessarily
needed, as the elements in question only get one or no class assigned.

I've dropped no longer supported css options like:

the appearance option isn't supported by any browser, the -webkit-appearance
doesn't change anything visible.

-webkit-font-smoothing support was dropped in chrome 22 and font-smoothing
isn't specified anywhere.
remove multiple definition of data-item-page
Fever API: Allow to select the database

Utilize apaches mod_rewrite to append a database parameter to the fever
api script based on the requested URL. Basically everything after
/fever/ is treated as the desired database. E.g. using
https://www.miniflux.net/fever/custom.sqlite/ as server url selects this
database as sync source/target.

The user supplied database parameter is compared with the output of
Model\Database\get_all(), which ensures that only files within the
DATA_DIRECTORY can be referenced (prevents File Inclusion/Directory
Traversal vulnerabilities).

I've tested it against Reeder on iOS. Note that Reeder does not allow
the same user name to be used multiple times within the same domain
name, even if the used URLs are different.
introduce integration tests