Display pending updates in the status messages

[oliv3]

This adds another functional test that is to display the number of pending updates.

Unsent positions count will appear in parenthesises.
Another way for the user to check for e.g. network issue.

[redge76]

I also interested by some statistical data but I don't think that adding only the number of pending locations to the "update" message is the right way.
I think you could use another "view" or keep the data in a "text box" at the top of the status page.
Another solution is to open a "Dialog" when you touch one of the line. It's a good solution to display a lot of information.

Stats I'd like to see are:

• number of pending locations
• time since last update
• current GPS status & accuracy

Also, it is not obvious that the number in "( )" is the number of pending location.

[oliv3]

Feel free to send a PR. Can't spend more time on this, my customers are fine with the feature as it is.

[redge76]

ohhh it was also not obvious it was a dev for some customer.
My message was just a "user feedback" and I don't have much time too.... That's the way opensource go. Hard to find contributors... Sorry.

[oliv3]

It is fine to be integrated, as is. This PR is to off-load work on my side :)
Could surely be better to add some message for the () meaning, but when properly documented or explained, people understand.
And I don't think @tananaev does want to make the application complicated, (not to say user-friendly), so I decided to keep this bare bones.

[oliv3]

@redge76 also, this feature would have to be coded for iOS, for it to be merged by @tananaev :(