fix lint and findbug warnings

Signed-off-by: Marcel Hibbe <dev@mhibbe.de>

app/src/main/res/drawable/ic_refresh_black_24dp.xml

@@ -1,25 +0,0 @@
-<!--
-  ~ Nextcloud Talk application
-  ~
-  ~ @author Mario Danic
-  ~ Copyright (C) 2017-2018 Mario Danic <mario@lovelyhq.com>
-  ~
-  ~ This program is free software: you can redistribute it and/or modify
-  ~ it under the terms of the GNU General Public License as published by
-  ~ the Free Software Foundation, either version 3 of the License, or
-  ~ at your option) any later version.
-  ~
-  ~ This program is distributed in the hope that it will be useful,
-  ~ but WITHOUT ANY WARRANTY; without even the implied warranty of
-  ~ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  ~ GNU General Public License for more details.
-  ~
-  ~ You should have received a copy of the GNU General Public License
-  ~ along with this program.  If not, see <http://www.gnu.org/licenses/>.
-  -->
-
-<vector android:autoMirrored="true" android:height="24dp"
-    android:viewportHeight="24.0" android:viewportWidth="24.0"
-    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
-    <path android:fillColor="#FF000000" android:pathData="M17.65,6.35C16.2,4.9 14.21,4 12,4c-4.42,0 -7.99,3.58 -7.99,8s3.57,8 7.99,8c3.73,0 6.84,-2.55 7.73,-6h-2.08c-0.82,2.33 -3.04,4 -5.65,4 -3.31,0 -6,-2.69 -6,-6s2.69,-6 6,-6c1.66,0 3.14,0.69 4.22,1.78L13,11h7V4l-2.35,2.35z"/>
-</vector>

app/src/main/res/values/strings.xml

@@ -333,7 +333,6 @@
 
     <!-- Browser component -->
     <string name="nc_file_browser_back">Back</string>
-    <string name="nc_file_browser_refresh">Refresh</string>
     <string name="nc_last_modified">%1$s | Last modified: %2$s</string>
     <string name="nc_file_browser_reshare_forbidden">You are not allowed to re-share this file</string>
     <string name="nc_sort_by">Sort by</string>

scripts/analysis/findbugs-results.txt

@@ -1 +1 @@
-596
+595

scripts/analysis/lint-results.txt

@@ -1,2 +1,2 @@
 DO NOT TOUCH; GENERATED BY DRONE
-      <span class="mdl-layout-title">Lint Report: 3 errors and 268 warnings</span>
+      <span class="mdl-layout-title">Lint Report: 3 errors and 266 warnings</span>