AD15 converter for OF 3.0 to OF 4.0 leaves AFAeroMod comments

[andrew-platt]

In the AD15 update for OpenFAST v4.0.0, the AFAeroMod option was replaced with the UA_Mod option (in combination with other options). However, when using the converter, comments may still contain AFAeroMod in the comment. For example, the following comment (line 10) is left as:
False CavitCheck - Perform cavitation check? (flag) [AFAeroMod must be 1 when CavitCheck=true]
but should be changed to
False CavitCheck - Perform cavitation check? (flag) [UA_Mod must be 0 when CavitCheck=true]

I took a look at the converter, but don't know python well enough to address this issue and make a PR.

[rthedin]

While this isn't complicated, it will only make sense for OpenFAST v > 4.0.0. Should we add tags to the openfast_toolbox releases as well? Old toolbox had tags and it was easier to match openfast and python-toolbox. See #7. This way we could add the appropriate comment to each tag.