HttpFeed supports authentication

Supply username and password to HttpFeed buider. Uses httpcomponents'
standard mechanisms, so Brooklyn handles everything httpcomponents handles.
Extends HttpService to create servers requiring basic authentication.

Conflicts:
	core/src/main/java/brooklyn/event/feed/http/HttpFeed.java
	core/src/test/java/brooklyn/event/feed/http/HttpFeedSslIntegrationTest.java
Enable AS7 management interface security by default

Adds MANAGEMENT_USER and MANAGEMENT_PASSWORD config keys to the AS7
entity. Username defaults to 'brooklyn', password to a random UUID.

Note that this uses import org.apache.commons.codec.binary.Hex to encode
a byte[] as a hex string rather than Guava's BaseEncoding because
Brooklyn 0.5 is on Guava 13 and BaseEncoding was added in Guava 14.

Conflicts:
	software/webapp/src/main/java/brooklyn/entity/webapp/jboss/JBoss7Server.java
	software/webapp/src/main/java/brooklyn/entity/webapp/jboss/JBoss7SshDriver.java
Merge pull request #799 from sjcorbett/as7-security-0.5-backport

AS7 security 0.5 backport