Use GitVersion to increment build numbers

[tobiasdiez]

Fixes #5399 and fixes #5657.
The following version information is automatically determined by GitVersion based on the current tags.

Context	Build version	Build information
PR	5.0.X	5.0-branch.Y
Master	5.0.X	5.0
After tag 5.1	5.1.X	5.1

Here, X is the number of commits since the last tag; and Y is the number of commits on this branch; and branch` is the branch name. Build version is the version used in gradle, i.e. the one used to generate the installer. Build information is what is displayed in the about dialog.
(Not sure if it really works on the master as it should; couldn't test it so far).

It should also work with tags of the form 5.0-beta (which have build version = 5.0.X and build information = 5.0-beta). Thus, this PR hopefully also solves the problems of #5684.

• Change in CHANGELOG.md described (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for bigger UI changes)
• Checked documentation: Is the information available and up to date? If not: Issue created at https://github.com/JabRef/user-documentation/issues.

[LinusDietz]

Good idea to use GitVersion, but it seems that it does not work. I've tried to push this to the v5.0-beta tag and it seems that the version detection does not work on a tag

https://github.com/JabRef/jabref/commit/e8cfdeca00e3780a45fdf4bb4334e401d4bb3809/checks?check_suite_id=337788976

INFO [12/02/19 14:00:39:99] Current commit is tagged with version 5.0.0-beta, version calculation is for metadata only.  WARN [12/02/19 14:00:40:00] An error occurred:
It looks like the branch being examined is a detached Head pointing to commit 'e8cfdec'. Without a proper branch name GitVersion cannot determine the build version.::error::SyntaxError: Unexpected token I in JSON at position 0

[tobiasdiez]

It's a problem with our github workflow, which expects a proper git ref to determine the branch name. The build works after you commit something else. Nonetheless, it seems like the beta part is not picked up properly. Easiest workaround: work on branch with name beta.

[tobiasdiez]

Update: this seems to be by design, as the branch name overwrites every other pre release label. https://gitversion.readthedocs.io/en/latest/configuration/#tag

Thus, it only works on master. In the worst case, we have to add

release:
    regex: ^releases?[/-]
    mode: ContinuousDelivery
    tag: beta
    prevent-increment-of-merged-branch-version: true
    track-merge-target: false
    tracks-release-branches: false
    is-release-branch: true

to the GitVersion config, and always deploy from the release branch (which might actually be a good idea regardless).

[tobiasdiez]

@LinusDietz building on a tag should now also work, if you still have problems with this on master.

[koppor]

We should disable the auto update check for version 0.0.1:

[tobiasdiez]

@koppor good point. I've now set the default version to 100.0.0, so we should never reach this.

For the sake of moving forward, I'll merge now. Let's see how it works on master.