Show year so far when clicking on current year

[FdelMazo]

Now, when clicking on the current year, the lastDay is set to the current date. This has two impacts:

• The average commit per day is now calculated taking the days in the year so far, instead of the whole year
• The Jan 1 -> Dec 31 on the total contributions chart is now replaced with a Jan 1 -> <currentdate>

Closes #316

[jasonlong]

@FdelMazo I was on vacation last week, but I'm back now and will check this out shortly. Thanks for the contribution.

[jasonlong]

Had a chance to test this out today and it seems to work great. Thanks for the contribution, @FdelMazo.

I will publish a new release after merging.