Override underlined links in button text

* Added "text-decoration: none" to button text;
* css file is loaded in the options page, too. Now the preview is displayed correctly.
* css file now is generated only on options update (used to be every time the options page is opened).
Deleted the extra slash in image URL

Solving bug https://github.com/ciubotaru/share-on-diaspora/issues/18.
Tab group added to options page.

Not functional yet. Just a mockup.
Tabs on the settings page are fully functional now

Just need to add content to the pod list tab.
Created options for tab #2 (pod list).
Minor fixes
Explicitly declared a global variable (array of default values)

This fixes bug https://github.com/ciubotaru/share-on-diaspora/issues/19.
Merge branch 'button-css' into unstable
changed filenames for pod lists
on activation empty options are set to defaults
pod_list_show.php created on tab2 update, css created on tab1 update
merging button-css into unstable
merging pod-list-options into unstable
fixed typo and updates uninstall
updated new_window.php, pod_list_show.php, share-on-diaspora.css, share-on-diaspora.php
updated pod list
updated readme.txt in trunk
updated screenshots
merged unstable into master