fix(i18n): use "Skype" instead of app.i18n.IDL("Skype")

This closes #147.
fix(i18n): use "localStorage" instead of app.i18n.IDL("LocalStorage")

This closes #148.
feat(settings): remove on/off button

This commit removes an on/off button from settings page.

You can disable extension/addon using standard browser tools,
so this button is considered WET.

This commit also introduces a feature: in vkoptSets object you
can use `raw` field instead of `id` and `text` to use that raw html
for particular setting.

See #146 for more.

This closes #146, closes #63.
feat(themes): remove themes

See #143 for more info.

Remove `vk_skinman.js` completely, and all the things regarding
custom site themes over other scripts (e.g. settings).

This closes #27, closes #61, closes #143.