Add device agent library

Provide enrollment, elevated install, posture checks, keystore, and
system-tray helpers shared by the probo-agent binary.

Signed-off-by: Ludovic Vielle <ludovic@probo.com>

pkg/deviceagent/service/launchd.plist.tmpl

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
+  "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>Label</key>
+    <string>{{xml .Label}}</string>
+    <key>ProgramArguments</key>
+    <array>
+        <string>{{xml .ExePath}}</string>
+        <string>run</string>
+        <string>--dir</string>
+        <string>{{xml .Dir}}</string>
+    </array>
+    <key>RunAtLoad</key>
+    <true/>
+    <key>KeepAlive</key>
+    <true/>
+    <key>StandardOutPath</key>
+    <string>/var/log/probo-agent.log</string>
+    <key>StandardErrorPath</key>
+    <string>/var/log/probo-agent.log</string>
+    <key>UserName</key>
+    <string>root</string>
+    <key>GroupName</key>
+    <string>wheel</string>
+</dict>
+</plist>