Server: New note flow improvements

Currently creating a new note works like this (quite cumbersome):
1. Click »New«
2. Need to manually focus the title field
3. Think of a title and type it in
4. Think if you need to add it to a group because the dropdown is shown to you at this step
5. Click »Create« (pay attention to not click »Cancel« which is directly next to it …)
6. Wait for the note to appear in the list, then click it manually
7. Click the content field manually to start typing.

Instead this could be way quicker, similar to the [Notes](https://github.com/owncloud/notes) app:
1. Click an entry »New note« which is the top item in the left sidebar
2. Directly open the note and focus the content area so people can quickly start typing. The title can be adjusted there (default is »New note«)

@Fmstrat @agnostikone @j-ed what do you think?