Improve event bubble margins

[David Planella]

Right now, when looking at events in e.g. day view, there are a couple of design issues that could be solved to make them a bit tidier and more readable:

- The top margin is too small: the event hour nearly sticks to the bubble's top edge
- The coloured circle to the left of the event time is too close to the left, it should probably be moved to the right, or replaced by colouring the whole bubble
- Often if the vertical length (duration) of an event is short, we cut the description halfway through withouth bottom margin. Rather than doing that, if the description does not fit completely in the bubble, we should probably not display it.

In short, we'd need an event bubble mockup with sizes and margin specifications.

[David Planella (dpm)]

Here are the guidelines from the design team (see the "Meeting headline here" event). In short:

- Calendar indicator (coloured circle) to the right
- 1 GU margins
- Do not show the second line if it's cut off

[Alan Pope 🍺🐧🐱 🦄 (popey)]

Related: bug 1304497

[Kunal Parmar (pkunal-parmar)]

How it should look in week view ?

[Ubuntu Phone Apps Jenkins Bot (ubuntu-phone-apps-jenkins-bot)]

Fix committed into lp:ubuntu-calendar-app at revision 268, scheduled for release in ubuntu-calendar-app, milestone alpha-1