AJP13 protocol parser

Tobias Begalke e4f4b07019 - added some bounds checks since munchclient crashed in production 7 lat temu
ajp13.go e4f4b07019 - added some bounds checks since munchclient crashed in production 7 lat temu
ajp13_test.go c0560ceda7 init 7 lat temu
header.go c0560ceda7 init 7 lat temu
method.go c0560ceda7 init 7 lat temu