Make an OSGi bundle

[tjwatson]

I would like to use this library as an OSGi bundle. This PR adds the necessary meta-data to build an OSGi bundle:

• Package org.checkpoint is exported as API
• OSGi Bundle-NativeCode header is used to inform the framework about native library
• Try System.loadLibrary("CheckpointRestore") first to allow the OSGi class loader to locate the native library packaged in the JAR before doing the manual extraction of the library to the /tmp folder.

This PR also includes adding common patterns to exclude to the .gitignore.

It also fixes the RandomTest package name. This test is in the package directory for org/checkpoint but it was using the default (empty) package name in the source. While javac and the maven usage of the java compiler cares nothing about the directory .java source files are located, I know some IDEs will give errors by default if it detects this type of thing. I think it would be nice to follow the convention if possible.

[judovana]

Hi! Pls wait with merging this untill javac -h is merged. As it is now moreover show stopper. If you can extract the test and sahde->jar hunks to separate PRs, woudl be awesome, as they can be merged asap. (Unlike the rest)

[judovana]

If you are still interested in osgi binding, I would be happy to finish the review.