enable support for grunt-newer

[wobblyrampack]

Would be beneficial in larget projects to only upload the changed files using grunt-newer.

[JaroslavMoravec]

But grunt-newer cannot be used for this. From grunt-newer's github page:

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Known limitations

The newer task relies on Grunt's convention for specifying src/dest mappings. So it should be expected to work with two types of tasks:

1. Tasks that specify both src and dest files. In this case, the task prefixed by newer will be configured to run with src files that are newer than the corresponding dest file (based on the mtime of files).

2. Tasks that specify only src files. In this case, the task prefixed by newer will be configured to run with src files that are newer than the previous successful run of the same task.

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https://github.com/tschaub/grunt-newer#known-limitations

[JaroslavMoravec]

@wobblyrampack Do you find a way to upload only newer files?