add .editorconfig

as per #14
close #14 (#14)

.editorconfig

@@ -0,0 +1,30 @@
+
+[*]
+charset = utf-8
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = tab
+indent_size = 4
+tab_width = 4
+
+[{*.har,*.jsb2,*.jsb3,*.json,.babelrc,.eslintrc,.stylelintrc,bowerrc,jest.config}]
+end_of_line = lf
+indent_style = space
+indent_size = 2
+
+[{*.yaml,*.yml}]
+end_of_line = lf
+indent_style = space
+indent_size = 2
+
+[*.js.map]
+end_of_line = lf
+indent_style = space
+indent_size = 2
+
+[*.{appxmanifest,asax,ascx,aspx,axaml,build,cg,cginc,compute,cs,cshtml,dtd,hlsl,hlsli,hlslinc,master,nuspec,paml,razor,resw,resx,skin,usf,ush,vb,xaml,xamlx,xoml,xsd}]
+end_of_line = lf
+indent_style = tab
+indent_size = 4
+tab_width = 4