Updated maven site plugin version and logos

[ingokegel]

After #37 a site update is advisable, because the new parameters are quite important, see #30

[jdillon]

was there any reason for the bytecode level change? its probably fine, and time to generally update to a more recent basis?

[jdillon]

why was src/site/resources/images/google-analytics.png removed?

[ingokegel]

was there any reason for the bytecode level change? its probably fine, and time to generally update to a more recent basis?

I updated it while trying to compile with Java 11, which does not support the 1.5 target anymore.

why was src/site/resources/images/google-analytics.png removed?

Sorry about that, I actually meant to update the logo, but something went wrong, I'll add it again on Monday.

[jdillon]

@ingokegel I'll just update the image, this project probably needs a bit of love to update all the various bits to modern deps, not sure I'll have time to do that any time soon though.