Fix #1981

As per discussion in #1981, change of line introduced in https://github.com/wenzhixin/bootstrap-table/commit/6e3410c275e25cba60013c415518ca7c46dc9277 causes issues with filtered columns

src/extensions/filter-control/bootstrap-table-filter-control.js

@@ -519,7 +519,7 @@
     BootstrapTable.prototype.initSearch = function () {
         _initSearch.apply(this, Array.prototype.slice.apply(arguments));
 
-        if (this.options.sidePagination !== 'server') {
+        if (this.options.sidePagination === 'server') {
             return;
         }