Updated readme with travis badges.
Updated readme with travis badges.

nblumhardt/serilog,clarkis117/serilog,merbla/serilog,ravensorb/serilog,harishjan/serilog,ravensorb/serilog,colin-young/serilog,joelweiss/serilog,harishjan/serilog,serilog/serilog,serilog/serilog,adamchester/serilog,clarkis117/serilog,skomis-mm/serilog,merbla/serilog,skomis-mm/serilog,colin-young/serilog,nblumhardt/serilog,adamchester/serilog,CaioProiete/serilog,joelweiss/serilog