Update master version to 1.5.0-beta1
Update master version to 1.5.0-beta1

OmniSharp/omnisharp-vscode,OmniSharp/omnisharp-vscode,OmniSharp/omnisharp-vscode,seraku24/omnisharp-vscode,gregg-miskelly/omnisharp-vscode,gregg-miskelly/omnisharp-vscode,gregg-miskelly/omnisharp-vscode,OmniSharp/omnisharp-vscode,gregg-miskelly/omnisharp-vscode,seraku24/omnisharp-vscode,OmniSharp/omnisharp-vscode