Plugin TAG: Adding multiple tags by business rules at the time time or appending new tags in sequential rules.

Currently it is not possible to add 2 or more tags in the same rule, only one tag.
And when we split in several rules (for instance 3 rules to add 3 tags) when the 3 rules are applicable to the same ticket, the ticket is updated only with the tag of the last rule, it means, it is not adding the new tags, but replacing the one tag that was added in the previous rule.

For example:

Categories:
"Correct security issues in Linux Server".
"Correct security issues in Windows Server".

The rules are set in Add/Update ticket:

• If category = "Correct security issues in Linux Server", add tag "Security".
• If category = "Correct security issues in Windows Server", add tag "Security".
• If category = "Correct security issues in Linux Server", add tag "Linux".
• • If category = "Correct security issues in Windows Server", add tag "Windows".

A new issue was added with category = "Correct security issues in Linux Server", and should be set with the tags "Security" AND "Linux", but currently when executed both rules, the issue is set only with "Linux". When I remove the Linux rule, the added issue was set with "Security" rule.
It means that the rule is replacing/subscribing all tags of the ticket, instead of add a new tag and maintain the old tags previous existent.

Usually when we decide to use tags we want to use several tags in the same ticket... not only 1 tag.

Obs.: see issue https://github.com/pluginsGLPI/tag/issues/229