#13 Added variant (flavor) support

[dpreussler]

No description provided.

[dpreussler]

some explaination how we use this with this PR:

flavors would be configured like this:

poeditor {
    apikey 'XXXXXX'
    type 'android_strings'
    tagsNew '1.0'
}
..
android {
  productFlavors {
      mtv {
            applicationId "...."
            project.poeditor {
                variant 'mtv'
                projectId 'XXXXX'
                terms 'app/src/mtv/res/values/strings.xml'
                trans 'en-us', 'app/src/mtv/res/values/strings.xml'
                trans 'es', 'app/src/mtv/res/values-es/strings.xml'
               ...
            }
        }

[a-manumohan]

@lukin0110 Can you please merge this PR? Thanks