[TravisCI] use the archive site to download flex sdk

Such that next time there is a new flex sdk release, the old url would still work.

tests/RunCi.hx

@@ -571,7 +571,7 @@ class RunCi {
 
 					//setup flex sdk
 					var flexVersion = "4.14.0";
-					runCommand("wget", ['http://mirror.cc.columbia.edu/pub/software/apache/flex/${flexVersion}/binaries/apache-flex-sdk-${flexVersion}-bin.tar.gz'], true);
+					runCommand("wget", ['http://archive.apache.org/dist/flex/${flexVersion}/binaries/apache-flex-sdk-${flexVersion}-bin.tar.gz'], true);
 					runCommand("tar", ["-xf", 'apache-flex-sdk-${flexVersion}-bin.tar.gz', "-C", Sys.getEnv("HOME")]);
 					var flexsdkPath = Sys.getEnv("HOME") + '/apache-flex-sdk-${flexVersion}-bin';
 					Sys.putEnv("PATH", Sys.getEnv("PATH") + ":" + flexsdkPath + "/bin");