[GH-3] Fix downloading remote_file connector-java

Replaced remote_file "mysql-connector-java.x.x.x.tar.gz"
    :create_if_missing by :create

Fixes the "taken no action" when the remote_file already exists,
while it should match the checksum to determine to download or not.
Merge pull request #4 from Rud5G/github-issue-3

[GH-3] Fix downloading remote_file connector-java