[spring-boot-gradle-plugin] Add support for environments in gradle

[raderio]

We have 3 properties file

application.properties
application-local.properties
application-dev.properties

application.properties
spring.profiles.active=@environment@

build.gradle

if (! hasProperty("environment")) {
    ext.environment = "local"
}

processResources {
    exclude {
        it.file.name ==~ Pattern.compile("application-((?!$environment).)*\\.properties")
    }
    filter(ReplaceTokens, tokens: [environment: environment])
}

./gradlew -Penvironment=dev run

Please add something similar to this in plugin.

[wilkinsona]

Duplicates #1176.