Remove form with POST action on Update Repo button

Since the Update action does not result in any actual modifications,
there is no need to use an HTML form for the Update Repository button on
the Manage Repository page.

Using a simple link button allows refreshing the Update Repository page
without having to re-send non-existent form data.

Fixes #300

Author: dregad

Source/pages/repo_manage_page.php

@@ -132,9 +132,13 @@ function convert_to_key_value( $p_array ) {
 			</div>
 			<div class="widget-toolbox padding-8 clearfix">
 				<div class="col-md-6 col-xs-12 no-padding">
-					<form action="<?php echo plugin_page( 'repo_update_page' ) . '&amp;id=' . $t_repo->id ?>" method="post" class="pull-left">
-						<input type="submit" class="btn btn-primary btn-white btn-sm btn-round" value="<?php echo plugin_lang_get( 'update_repository' ) ?>"/>
-					</form>
+					<?php
+					print_link_button(
+						plugin_page( 'repo_update_page' ) . '&id=' . $t_repo->id,
+						plugin_lang_get( 'update_repository' ),
+						'btn-sm pull-left'
+					);
+					?>
 					<form action="<?php echo plugin_page( 'repo_delete' ) . '&amp;id=' . $t_repo->id ?>" method="post" class="pull-left">
 						<?php echo form_security_field( 'plugin_Source_repo_delete' ) ?>
 						<input type="submit" class="btn btn-primary btn-white btn-sm btn-round" value="<?php echo plugin_lang_get( 'delete_repository' ) ?>"/>