Run and Exec now use passed in runtime and arch

src/dnvm.ps1

@@ -1598,7 +1598,7 @@ function dnvm-run {
         [Parameter(Mandatory=$false, Position=1, ValueFromRemainingArguments=$true)]
         [object[]]$DnxArguments)
 
-    $runtimeInfo = Get-RuntimeAliasOrRuntimeInfo -Version:$VersionOrAlias
+    $runtimeInfo = Get-RuntimeAliasOrRuntimeInfo -Version:$VersionOrAlias -Runtime:$Runtime -Architecture:$Architecture
 
     $runtimeBin = Get-RuntimePath $runtimeInfo.RuntimeName
     if ($runtimeBin -eq $null) {
@@ -1639,7 +1639,7 @@ function dnvm-exec {
         [Parameter(Mandatory=$false, Position=2, ValueFromRemainingArguments=$true)]
         [object[]]$Arguments)
 
-    $runtimeInfo = Get-RuntimeAliasOrRuntimeInfo -Version:$VersionOrAlias 
+    $runtimeInfo = Get-RuntimeAliasOrRuntimeInfo -Version:$VersionOrAlias -Runtime:$Runtime -Architecture:$Architecture
     $runtimeBin = Get-RuntimePath $runtimeInfo.RuntimeName
 
     if ($runtimeBin -eq $null) {

src/dnvm.sh

@@ -684,9 +684,9 @@ dnvm()
             local arch=
             local runtime=
 
+            local versionOrAlias=
             shift
             if [ $cmd == "use" ]; then
-                local versionOrAlias=
                 while [ $# -ne 0 ]
                 do
                     if [[ $1 == "-p" || $1 == "-persistent" ]]; then
@@ -706,8 +706,20 @@ dnvm()
                     shift
                 done
             else
-                local versionOrAlias=$1
+                while [ $# -ne 0 ]
-                shift
+                do
+                    if [[ $1 == "-a" || $1 == "-arch" ]]; then
+                        local arch=$2
+                        shift
+                    elif [[ $1 == "-r" || $1 == "-runtime" ]]; then
+                        local runtime=$2
+                        shift
+                    elif [[ -n $1 ]]; then
+                        [[ -n $versionOrAlias ]] && break
+                        local versionOrAlias=$1
+                    fi
+                    shift
+                done
             fi
 
             if [[ $cmd == "use" && $versionOrAlias == "none" ]]; then