Eliminate reserved 'default' profile (SPR-7778)

There is no longer a reserved default profile named 'default'. Rather,
users must explicitly specify a default profile or profiles via

    ConfigurableEnvironment.setDefaultProfiles(String...)
        - or -
    spring.profile.default="pD1,pD2"

Per above, the setDefaultProfile(String) method now accepts a variable
number of profile names (one or more).  This is symmetrical with the
existing setActiveProfiles(String...) method.

A typical scenario might involve setting both a default profile as a
servlet context property in web.xml and then setting an active profile
when deploying to production.

org.springframework.context/src/main/java/org/springframework/context/annotation/Profile.java

@@ -27,12 +27,13 @@ import java.lang.annotation.Target;
  * TODO SPR-7508: document
  * 
  * Components not @Profile-annotated will always be registered
- * @Profile("default") means that beans will be registered unless other profile(s) are active
- * @Profile({"xyz,default"}) means that beans will be registered if 'xyz' is active or if no profile is active
- * ConfigurableEnvironment.setDefaultProfileName(String) customizes the name of the default profile
- * 'spring.profile.default' property customizes the name of the default profile (usually for use as a servlet context/init param)
  * ConfigurableEnvironment.setActiveProfiles(String...) sets which profiles are active
  * 'spring.profile.active' sets which profiles are active (typically as a -D system property)
+   servlet context/init param)
+ * ConfigurableEnvironment.setDefaultProfiles(String...) or 'spring.profile.default' property specifies one
+   or more default profiles, e.g., 'default'
+ * if 'default' is specified as a default profile, @Profile({"xyz,default}) means that beans will be
+   registered if 'xyz' is active or if no profile is active
  *
  * @author Chris Beams
  * @since 3.1