Multiple improvements to the data hub:

* Making registration finer-grained so we only listen to the data we really need.
* Moving the system listener registration to an external class (for testability and readability)
* Adding a unit test (not yet complete)
* Adding documention and cleaning up comments

Still many things TODO:
* Allow pausing of registrations
* Add pause/resume to onPause/onResume of activities
* Move sampling logic out of the hub
* Optimize data reloading when display preferences change
* (maybe) move the data hub and related classes to the "content" package

SignalStrengthSamplerTest/.settings/org.eclipse.jdt.core.prefs

@@ -0,0 +1,12 @@
+#Sun Nov 28 01:19:10 PST 2010
+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.6
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=1.6
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.source=1.6