Add appstream XML file (#536)

src/Cutter.appdata.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<component type="desktop">
+  <id>Cutter.desktop</id>
+  <metadata_license>CC0-1.0</metadata_license>
+  <project_license>GPL-3.0</project_license>
+  <name>Cutter</name>
+  <summary>A Qt and C++ GUI for radare2 reverse engineering framework</summary>
+  <description>
+    <p>
+      Cutter is Qt and C++ GUI for radare2, originally named Iaito. It is not aimed at existing radare2 users, but focuses on those whose aren’t fluent yet with the command line, likely because of the steep learning curve.
+    </p>
+  </description>
+  <screenshots>
+    <screenshot>
+      <image>https://raw.githubusercontent.com/radareorg/cutter/master/docs/screenshot.png</image>
+      <caption>Main UI</caption>
+    </screenshot>
+    <screenshot>
+      <image>http://beta.rada.re/en/latest/_images/cutter.png</image>
+      <caption>Light Theme</caption>
+    </screenshot>
+    <screenshot>
+      <image>http://beta.rada.re/en/latest/_images/cutter_dark.jpg</image>
+      <caption>Dark Theme</caption>
+    </screenshot>
+  </screenshots>
+  <url type="homepage">http://beta.rada.re/en/latest/cutter.html</url>
+  <releases>
+    <release version="1.4" date="2018-04-24" />
+    <release version="1.3" date="2018-03-09" />
+    <release version="1.2" date="2018-01-30" />
+    <release version="1.1" date="2017-12-25" />
+    <release version="1.0" date="2017-12-03" />
+  </releases>
+</component>

src/Cutter.pro

@@ -315,13 +315,18 @@ unix {
 
     desktop_file = Cutter.desktop
 
-    # built-in no need for files atm
-    target.path = $$PREFIX/bin
-
     share_applications.path = $$PREFIX/share/applications
     share_applications.files = $$desktop_file
 
-    INSTALLS += target share_applications share_pixmaps
+    appstream_file = Cutter.appdata.xml
+
+    share_appdata.path = $$PREFIX/share/appdata
+    share_appdata.files = $$appstream_file
+
+    # built-in no need for files atm
+    target.path = $$PREFIX/bin
+
+    INSTALLS += target share_appdata share_applications share_pixmaps
 
     # Triggered for example by 'qmake APPIMAGE=1'
     !isEmpty(APPIMAGE){