Add email support

This commit adds a new starter to auto-configure a MailSender when the
necessary classes are present and when the property "spring.mail.host" is
set.

The auto-configuration also accepts any arbitrary properties that
JavaMail might need using the "spring.mail.properties" prefix.

Fixes gh-1760

spring-boot-starters/pom.xml

@@ -43,6 +43,7 @@
 		<module>spring-boot-starter-logging</module>
 		<module>spring-boot-starter-log4j</module>
 		<module>spring-boot-starter-log4j2</module>
+		<module>spring-boot-starter-mail</module>
 		<module>spring-boot-starter-mobile</module>
 		<module>spring-boot-starter-actuator</module>
 		<module>spring-boot-starter-parent</module>

spring-boot-starters/spring-boot-starter-mail/pom.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starters</artifactId>
+		<version>1.2.0.BUILD-SNAPSHOT</version>
+	</parent>
+	<artifactId>spring-boot-starter-mail</artifactId>
+	<name>Spring Boot Mail Starter</name>
+	<description>Spring Boot Mail Starter</description>
+	<url>http://projects.spring.io/spring-boot/</url>
+	<organization>
+		<name>Pivotal Software, Inc.</name>
+		<url>http://www.spring.io</url>
+	</organization>
+	<properties>
+		<main.basedir>${basedir}/../..</main.basedir>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-core</artifactId>
+			<exclusions>
+				<exclusion>
+					<groupId>commons-logging</groupId>
+					<artifactId>commons-logging</artifactId>
+				</exclusion>
+			</exclusions>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-context</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-context-support</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>javax.mail</groupId>
+			<artifactId>mail</artifactId>
+		</dependency>
+	</dependencies>
+</project>

spring-boot-starters/spring-boot-starter-mail/src/main/resources/META-INF/spring.provides

@@ -0,0 +1 @@
+provides: spring-context-support,mail