[ImgBot] Optimize images

*Total -- 775.52kb -> 686.88kb (11.43%)

/graphs/web1/response-time-day.png -- 10.36kb -> 3.58kb (65.39%)
/graphs/web4/response-time-day.png -- 10.42kb -> 3.71kb (64.4%)
/graphs/web2/response-time-day.png -- 10.63kb -> 3.87kb (63.58%)
/graphs/web7/response-time-day.png -- 11.84kb -> 4.77kb (59.72%)
/graphs/web6/response-time-day.png -- 6.92kb -> 3.74kb (45.95%)
/graphs/web5/response-time-day.png -- 3.31kb -> 1.82kb (44.93%)
/graphs/thundersquared/response-time-day.png -- 3.78kb -> 2.32kb (38.73%)
/graphs/web2/response-time-week.png -- 15.95kb -> 13.64kb (14.5%)
/graphs/web4/response-time-week.png -- 16.30kb -> 13.98kb (14.24%)
/graphs/web6/response-time-week.png -- 15.85kb -> 13.76kb (13.18%)
/graphs/web1/response-time-week.png -- 16.11kb -> 14.11kb (12.43%)
/graphs/thundersquared/response-time-week.png -- 15.73kb -> 13.98kb (11.14%)
/graphs/web6/response-time-year.png -- 35.37kb -> 31.57kb (10.73%)
/graphs/web6/response-time.png -- 35.37kb -> 31.57kb (10.73%)
/graphs/web7/response-time-week.png -- 14.52kb -> 12.97kb (10.69%)
/graphs/web5/response-time-week.png -- 16.16kb -> 14.47kb (10.5%)
/graphs/web2/response-time-year.png -- 35.36kb -> 32.09kb (9.25%)
/graphs/web2/response-time.png -- 35.36kb -> 32.09kb (9.25%)
/graphs/web7/response-time-month.png -- 26.46kb -> 24.30kb (8.17%)
/graphs/web6/response-time-month.png -- 25.28kb -> 23.45kb (7.26%)
/graphs/web7/response-time.png -- 39.65kb -> 36.86kb (7.03%)
/graphs/web7/response-time-year.png -- 39.65kb -> 36.86kb (7.03%)
/graphs/web4/response-time-month.png -- 26.21kb -> 24.45kb (6.72%)
/graphs/web2/response-time-month.png -- 26.67kb -> 24.94kb (6.5%)
/graphs/web1/response-time-month.png -- 26.65kb -> 24.97kb (6.32%)
/graphs/thundersquared/response-time.png -- 39.84kb -> 37.39kb (6.16%)
/graphs/thundersquared/response-time-year.png -- 39.84kb -> 37.39kb (6.16%)
/graphs/web5/response-time-year.png -- 39.63kb -> 37.60kb (5.13%)
/graphs/web5/response-time.png -- 39.63kb -> 37.60kb (5.13%)
/graphs/thundersquared/response-time-month.png -- 26.85kb -> 25.51kb (4.99%)
/graphs/web5/response-time-month.png -- 27.39kb -> 26.23kb (4.25%)
/graphs/web4/response-time-year.png -- 21.21kb -> 20.66kb (2.62%)
/graphs/web4/response-time.png -- 21.21kb -> 20.66kb (2.62%)

Signed-off-by: ImgBotApp <ImgBotHelp@gmail.com>

Author: ImgBotApp