renamed user folder to correspond to original github username

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rename : contributors/ttwf_tokyo/junichikawa/submitted/filters-drop-shadow-ref.html => contributors/ttwf_tokyo/sparkgene/submitted/filters-drop-shadow-ref.html
rename : contributors/ttwf_tokyo/junichikawa/submitted/filters-drop-shadow.html => contributors/ttwf_tokyo/sparkgene/submitted/filters-drop-shadow.html