update irony-mode recipe and add a new one: company-irony

Hello,

I'm the author of irony-mode but I reorganized the code structure and the git branches, now the old recipe is broken.

This PR updates the recipe to handle the new layout (it's simpler now) and adds [company-irony](https://github.com/Sarcasm/company-irony).

I ran the test scripts, it works:

    *** SUCCESS recipes/company-irony.rcp ***

But it seems like for `irony-mode` the .dir-locals.el is byte-compiled, wouldn't make sense to exclude them?

    el-get-byte-compile: .dir-locals.el
    Local variables list is not properly terminated
    Local variables list is not properly terminated