Add eclipse specific profile to set execution env

Update the parent POM to include a new profile which is automatically
enabled by eclipse.

The profile duplicates `default` and also set the compiler version to
1.8. This means that M2E sets the execution environment to `JavaSE-1.8`
but the command line build still compiles 1.6 compatible code.

Fixes gh-3618

spring-boot-parent/pom.xml

@@ -572,6 +572,74 @@
 				</pluginRepository>
 			</pluginRepositories>
 		</profile>
+		<profile>
+			<id>eclipse.profile</id>
+			<activation>
+				<property>
+					<name>m2e.version</name>
+				</property>
+			</activation>
+			<build>
+				<plugins>
+					<plugin>
+						<!-- Up the compiler version so the correct execution environment is used -->
+						<!-- The profile is only active in eclipse so we still target 1.6  on the command line -->
+						<groupId>org.apache.maven.plugins</groupId>
+						<artifactId>maven-compiler-plugin</artifactId>
+						<configuration>
+							<source>1.8</source>
+							<target>1.8</target>
+						</configuration>
+					</plugin>
+				</plugins>
+			</build>
+			<repositories>
+				<repository>
+					<id>spring-ext</id>
+					<url>http://repo.spring.io/ext-release-local/</url>
+					<releases>
+						<enabled>true</enabled>
+					</releases>
+					<snapshots>
+						<enabled>false</enabled>
+					</snapshots>
+				</repository>
+				<repository>
+					<id>spring-milestones</id>
+					<name>Spring Milestones</name>
+					<url>http://repo.spring.io/milestone</url>
+					<snapshots>
+						<enabled>false</enabled>
+					</snapshots>
+				</repository>
+				<repository>
+					<id>spring-snapshots</id>
+					<name>Spring Snapshots</name>
+					<url>http://repo.spring.io/snapshot</url>
+					<snapshots>
+						<enabled>true</enabled>
+					</snapshots>
+				</repository>
+			</repositories>
+			<pluginRepositories>
+				<pluginRepository>
+					<id>spring-milestones</id>
+					<name>Spring Milestones</name>
+					<url>http://repo.spring.io/milestone</url>
+					<snapshots>
+						<enabled>false</enabled>
+					</snapshots>
+				</pluginRepository>
+				<pluginRepository>
+					<id>spring-snapshots</id>
+					<name>Spring Snapshots</name>
+					<url>http://repo.spring.io/snapshot</url>
+					<snapshots>
+						<enabled>true</enabled>
+					</snapshots>
+				</pluginRepository>
+			</pluginRepositories>
+		</profile>
 		<profile>
 			<id>prepare</id>
 			<repositories>