fix closing search dropdown (#1142)

* using a different library for javascript selects, fixing the closing search dropdown
* fix closing dropdown for daterangepicker
* added missing search button for mobile on customer page
* fix meta fields with same names than existing columns

assets/sass/admin-lte.scss

@@ -0,0 +1,10 @@
+
+$icon-font-path: "~bootstrap-sass/assets/fonts/bootstrap/";
+$fa-font-path: "~@fortawesome/fontawesome-free/webfonts/";
+
+@import '~bootstrap-sass/assets/stylesheets/bootstrap';
+@import '~@fortawesome/fontawesome-free/scss/fontawesome';
+@import '~@fortawesome/fontawesome-free/scss/regular';
+@import '~@fortawesome/fontawesome-free/scss/solid';
+@import '~@fortawesome/fontawesome-free/scss/brands';
+@import '~daterangepicker/daterangepicker.css';

assets/sass/app.scss

@@ -5,7 +5,6 @@
  * file that was distributed with this source code.
  */
 
-@import "~bootstrap-sass/assets/stylesheets/bootstrap/variables";
 @import 'variables';
 @import 'error-page';
 @import 'print';
@@ -24,3 +23,4 @@
 @import 'skins';
 @import 'sweetalert';
 @import 'autocomplete';
+@import 'selectpicker';

assets/sass/selectpicker.scss

@@ -0,0 +1,23 @@
+@import '~select2/dist/css/select2.min.css';
+@import '~select2-bootstrap-theme/dist/select2-bootstrap.min.css';
+
+/* some labels were placed incorrect due to a margin-top: -4px */
+.select2-container .select2-selection--single .select2-selection__rendered {
+    margin-top: 0;
+}
+/* make sure the border looks like all other form elements */
+.select2-container--bootstrap .select2-selection {
+    border-radius: 0;
+}
+/* placeholder in multi-selects were cut off */
+.select2-search.select2-search--inline .select2-search__field {
+    width: 100% !important;
+}
+/* make sure that <optgroup> elements are padded, to allow visual difference to global activities */
+.select2-container--bootstrap .select2-results__options.select2-results__options--nested li.select2-results__option {
+    padding-left: 30px;
+}
+/* empty <option> were too small to be noticed as clickable element */
+.select2-container--bootstrap .select2-results__option {
+    min-height: 30px;
+}

assets/sass/variables.scss

@@ -5,6 +5,8 @@
  * file that was distributed with this source code.
  */
 
+@import "~bootstrap-sass/assets/stylesheets/bootstrap/variables";
+
 /**
  * A simple one to one clone of /node_modules/admin-lte/build/less/variables.less
  */