allow running on linux more easily

Contentless/Contentless.nuspec

@@ -2,7 +2,7 @@
 <package>
     <metadata>
         <id>Contentless</id>
-        <version>3.0.2</version>
+        <version>3.0.3</version>
         <authors>Ellpeck</authors>
         <description>A tool for MonoGame that automatically handles adding assets to the Content Pipeline project</description>
         <tags>monogame mono xna content pipeline mgcb builder tool library</tags>

Contentless/Contentless.targets

@@ -1,5 +1,12 @@
 <Project>
     <Target Name="Contentless" BeforeTargets="BeforeBuild">
-        <Exec Command="$(MSBuildThisFileDirectory)/../tools/Contentless.exe @(MonoGameContentReference)"/>
+        <PropertyGroup Condition="'$(OS)' != 'Windows_NT'">
+            // We use mono to run Contentless when we're not on Windows. This isn't pretty, but it'll do until we switch to the new task system.
+            <Mono Condition="Exists('/Library/Frameworks/Mono.framework/Versions/Current/bin/mono')">/Library/Frameworks/Mono.framework/Versions/Current/bin/mono</Mono>
+            <Mono Condition="Exists('/usr/local/bin/mono')">/usr/local/bin/mono</Mono>
+            <Mono Condition="Exists('/usr/bin/mono')">/usr/bin/mono</Mono>
+            <Mono Condition="'$(Mono)' == ''">mono</Mono>
+        </PropertyGroup>
+        <Exec Command="$(Mono) $(MSBuildThisFileDirectory)/../tools/Contentless.exe @(MonoGameContentReference)"/>
     </Target>
 </Project>

NuGet.config

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<configuration>
-    <config>
-        <add key="globalPackagesFolder" value="..\.nuget\packages" />
-    </config>
-</configuration>