Series sales form: don't specify primary currency by default.

Should prevent accidentally submitting a form with default currency.

Author: php-coder

Diff for: src/main/webapp/WEB-INF/views/series/info.html

@@ -449,6 +449,7 @@ <h5 th:text="|#{t_add_info_who_selling_series}:|">Add info about selling/buying
 													</div>
 													<div class="col-xs-4 no-padding">
 														<select id="currency" class="form-control" required="required" th:field="*{currency}">
+															<option value=""></option>
 															<option value="USD">USD</option>
 															<option value="EUR">EUR</option>
 															<option value="GBP">GBP</option>