Fail convert if "convert_to" consists of three parts

[arnisoft]

To convert a document to HTML with embdedded images, you must use convert_to param 'html:HTML:EmbedImages'.
For example:
Libreconv.convert('document.docx', '/Users/ricn/pdf_documents/my_document_as.html', nil, 'html:HTML:EmbedImages')

But this code fail at

target_tmp_file = File.join(
          target_path,
          File.basename(@escaped_source_path, '.*') + '.' +
            File.basename(@convert_to, ':*')
        )

because generating output filename extension File.basename(@convert_to, ':*') returns 'html:HTML'.
This is incorrect filename extension.

I think code
File.basename(@convert_to, ':*')
must be replaced by something like this
@convert_to.split(':').first

[ndbroadbent]

Ah, thanks for letting me know about that! Would you have some time to add a new test case for a doc with embedded images? The test could ensure that the HTML contains some expected test, and the the images are embedded properly. It would be great if you could please submit a PR to fix this issue. Thanks!

[yhirano55]

@ndbroadbent Pull request #35 has resolved this issue. Could you please review the changes and confirm that they have addressed the problem?