JCLOUDS-653: Upgrade to Guava 18.0

Release notes:

https://code.google.com/p/guava-libraries/wiki/Release18
Add whitespace after semicolons

Also correct some bad line-wrapping.
Enforce whitespace after semicolon
Remove spurious whitespace

Also remove spurious unary operator plus.
Enforce no leading or trailing spurious whitespace
Enforce type naming via Checkstyle
Prevent instantiation of utility classes

Also prevent extension.
Ignore jEnv files
Remove redundant modifiers from interfaces
Enforce no redundant modifiers via Checkstyle

This check also helps find utility classes which should not allow
instantiation.
Avoid primitive wrapper constructors
Ensure no calls to primitive wrapper constructors
Upgrade to maven-findbugs-plugin 3.0.0

Notably this release include support for Java 8.  Changelog:

http://findbugs.sourceforge.net/Changes.html
Use randomByteSource to generate test data

This avoids buffering the entire bolus of data in-memory.
jclouds Development Tools
Set Content-MD5 only if ETag has correct format

Previously this check was more lenient than it should have been.
Correct unusual equals implementations

Found with FindBugs.
Avoid unnecessary boxing

Found with FindBugs.
Miscellaneous FindBugs fixes
Add suppressions to FindBugs