migration: competitors:user must not be null

This is to make sure seeds are OK, as you cannot make an application
without setting a valid user.

This might actually change later as we add redundancy to the
competitor, covering, for instance, a case where user object
is deleted (i.e. user deletes her profile) and a competitor in
a competition stays.

And it already showed us problems with the user with three
names and several others. This commit fixes them all, hopefully.

Signed-off-by: Zeljko <zeljko@zwr.fi>
fix: allow name to be updated

This is one Devise catch which was obviously a bug:
name was allowed to be sent to server in sign_up, but not
in account_update, and for sign_up it was allowed twice.

Now you can change your name in the profile page.

Signed-off-by: Zeljko <zeljko@zwr.fi>
bootstrap the layout

Added bootstrap and created the first main page layout
with lists of past and future events. Logical sign in/up/out
links included in navbar.

Signed-off-by: Zeljko <zeljko@zwr.fi>
add hash to alert and notice

Signed-off-by: Zeljko <zeljko@zwr.fi>
event period

Shows the period when the event takes place, if one day
then shows the date, otherwise shows the date-span:

1.7.2015
1.-4.7.2015
29.6.-1.7.2015

Signed-off-by: Zeljko <zeljko@zwr.fi>
show event: tabbed pages

Now using bootstrap tabs to show pages, still pages are text not
de-markdowned.

Signed-off-by: Zeljko <zeljko@zwr.fi>