Introduce Che Omnisharp Plugin (#107)

Introduce new plugin for C# language support

Signed-off-by: Valeriy Svydenko <vsvydenk@redhat.com>

plugins/che-omnisharp-plugin/0.0.1/meta.yaml

@@ -0,0 +1,12 @@
+id: che-omnisharp-plugin
+version: 0.0.1
+type: Theia plugin
+name: Omnisharp Theia Plug-in
+title: C# Language Support for Theia
+description: This plug-in registers omnisharp-roslyn as a language server and provides project dependencies and language syntax.
+url: /~https://github.com/redhat-developer/omnisharp-theia-plugin/releases/download/v0.0.1/omnisharp_theia_plugin.theia
+icon: https://www.eclipse.org/che/images/logo-eclipseche.svg
+publisher: Red Hat, Inc.
+repository: /~https://github.com/redhat-developer/omnisharp-theia-plugin
+category: Language
+firstPublicationDate: "2019-03-13"