versionwatch should ignore latest symlinks when loading new installers against which to compare

Since adding a "latest jar" symlink into the JBDS installer build folders, eg.,

https://devstudio.redhat.com/9.0/snapshots/builds/devstudio.product_9.0.mars/latest/all/jboss-devstudio-9.1.0.latest-installer-standalone.jar

we now get a "jbds-9.1.0.latest" installation into ~/static_build_env/jbds/versionwatch/installations. But this folder does not get updated when newer installers are created, so we should ensure that the latest symlinks are NOT used to produce a latest installation folder.

Otherwise we end up with false positive errors like:

Version decreased issues
com.spotify.docker.client	3.1.10.v20151113-2033

when compared to 3.1.1 in a "seen as newer" (but built earlier so older) latest build.