Change perf_time to float type

- migration
- models/perf.erb : .to_f ; %2N au lieu de %L ;
- view _perftable.html.erb : modify affichage perf_time
- view perfs/show.html.erb : idem
fixed fractional seconds issue

- migration : float => décimal pour perf_time
- correction model perf
minor change

commented coffee script alert
fixed search

supprimé hidden_field_tag
Merge branch 'change-perf_time-to-float-type'

Conflicts:
	swimrecord.sublime-workspace