Improved: Replace Bintray by a new place to upload the Gradle Wrapper (OFBIZ-12192)

The checksum part was missing in Windows init-gradle-wrapper.ps1 script

I have noticed 2 points:
1. We should use SHA256, not SHA1
2. The unix-like shell script in OFBiz misses checksum verification in case
shasum command is not installed. In other words, if I launch the script it would
fail with "shasum not found, the downloaded files could not be verified".
However, the file will be kept there, so the user could launch unverified jar.

Last point was reported by Vladimir Sitnikov at LEGAL-288
1 file changed