[WFLY-3767] :  [WFLY-3767] : Update tools/maven handling in 8.x to match master
Replace bundled maven with version that is downloaded from Apache
Add windows powershell script to download maven
Upgrade to Maven 3.2.3
Remove the arg specifying the smoke testcase to be run within build.sh/build.bat.
This is anyways the default target of the testsuite.
So let's take the testsuite as master of specifying the tests to run by default.
Also changed the calls of the powershell to bypass the execution policy on the windows.