Release preparations for 1.9.9.1

Version bump, Changelog update, and minVersion bump. We've forgotten
the latter for a while now but this Torbutton requires at least a
Firefox 52.

src/CHANGELOG

+1.9.9.1
+ * Bug 25126: Make about:tor layout responsive
+ * Translations update
+
 1.9.9
  * Bug 24159: Version check does not deal with platform specific checks
  * Bug 25016: Remove 2017 donation banner

src/install.rdf

@@ -6,7 +6,7 @@
         <em:name>Torbutton</em:name>
         <em:creator>Mike Perry</em:creator>
         <em:id>torbutton@torproject.org</em:id>
-        <em:version>1.9.9</em:version>
+        <em:version>1.9.9.1</em:version>
         <em:multiprocessCompatible>true</em:multiprocessCompatible>
         <em:homepageURL>https://www.torproject.org/projects/torbrowser.html.en</em:homepageURL>
         <em:optionsURL>chrome://torbutton/content/preferences.xul</em:optionsURL>
@@ -17,7 +17,7 @@
         <em:targetApplication>
             <Description>
                 <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
-                <em:minVersion>45.0</em:minVersion>
+                <em:minVersion>52.0</em:minVersion>
                 <em:maxVersion>10000.0</em:maxVersion>
             </Description>
         </em:targetApplication>