Removed unnecessary gnuplot files.

commits_by_year.plot

@@ -1,5 +0,0 @@
-set terminal png
-set size 0.5,0.5
-set output 'commits_by_year.png'
-unset key
-plot 'commits_by_year.dat' using 1:2 w lp

commits_by_year_month.plot

@@ -1,8 +0,0 @@
-set terminal png
-set size 0.5,0.5
-set output 'commits_by_year_month.png'
-unset key
-set xdata time
-set timefmt "%Y-%m"
-set format x "%Y-%m"
-plot 'commits_by_year_month.dat' using 1:2 w lp

day_of_week.plot

@@ -1,6 +0,0 @@
-set terminal png
-set size 0.5,0.5
-set output 'day_of_week.png'
-unset key
-set xrange [0.5:7.5]
-plot 'day_of_week.dat' using 1:2:(0.5) w boxes fs solid