add gitbucket-csvtsv-plugin and gitbucket-smiles-plugin

[onukura]

This PR add plugins below to the community list.

• Plugin to render csv and tsv file https://github.com/onukura/gitbucket-csvtsv-plugin
• Plugin to render smiles file https://github.com/onukura/gitbucket-smiles-plugin

[onukura]

This one is better after #45 is checked and decided if merge or not.

[takezoe]

@onukura Merged #45. Could you revise this pull request?

[onukura]

@takezoe Thank you for merging #45. And I fixed this PR.

[takezoe]

Thanks for update!