Series sales form: don't set second currency to USD if price isn't specified.

Fix #675

Author: php-coder

Diff for: src/main/resources/liquibase/version/0.4.xml

@@ -30,5 +30,6 @@
 	<include file="0.4/2017-05-29--test_image.xml" relativeToChangelogFile="true" />
 	<include file="0.4/2017-10-23--image_filename.xml" relativeToChangelogFile="true" />
 	<include file="0.4/2017-10-30--scott_code_length.xml" relativeToChangelogFile="true" />
+	<include file="0.4/2017-10-31--series_sales_null_second_currency.xml" relativeToChangelogFile="true" />
 
 </databaseChangeLog>

Diff for: src/main/resources/liquibase/version/0.4/2017-10-31--series_sales_null_second_currency.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<databaseChangeLog
+		xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
+		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
+		http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.0.xsd">
+	
+	<changeSet id="nullify-series_sales-second_currency" author="php-coder" context="prod-data">
+		<comment>Sets to NULL the second_currency field if the second_price isn't specified</comment>
+		
+		<!-- Be caution: there is no rollback! -->
+		<sql>
+			UPDATE series_sales
+			   SET second_currency = NULL
+			 WHERE second_price IS NULL AND second_currency IS NOT NULL
+		</sql>
+		
+	</changeSet>
+	
+</databaseChangeLog>

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

@@ -478,6 +478,7 @@ <h5 th:text="|#{t_add_info_who_selling_series}:|">Add info about selling/buying
 													</div>
 													<div class="col-xs-4 no-padding">
 														<select id="alt-currency" class="form-control" th:field="*{altCurrency}">
+															<option value=""></option>
 															<option value="USD">USD</option>
 															<option value="EUR">EUR</option>
 															<option value="GBP">GBP</option>