Make modifications to the project descriptor.

- Modify pom.xml by adding obfuscation to build process.
- Fix pom.xml typos.
Make modifications to the project descriptor.

- Modify pom.xml by adding dependency for JSR 305 annotations, which expands the usefulness of the Findbugs plugin.
- Modify pom.xml by adding dependency for the Java binding of the Dropbox HTTP API.
Make modifications to the code formatter plugin configuration file.

- Modify the code formatter plugin configuration file by fixing a typo and formatting and aligning the XML,
Alter pom layout, add new dependencies and do general pom housekeeping. 

- Modify pom.xml by adding Codehaus Snapshot plugin repository to allow access to JDK8 compatible maven-findbugs-plugin.
- Modify pom.xml properties section by reorganizing properties by scope.
- Modify pom.xml plugins section by organizing plugins by there approximate exectuion order, pre-compile plugins first, then compile time plugins, and finally post-compile plugins.
- Adding animal-sniffer-plugin to verify API signatures are JDK7 compatible independent of the underlying JDK building the project.
- Modify findbugs-maven-plugin by removing some outdated configurations and changing the property used to define the location of the findbugs-excludes.xml file.
- Adding proguard-base-5.0beta2 dependency to the proguard-maven-plugin via a system scope hack (this dependency is not in the final artifact because it is a plugin dependency) that should be removed ASAP (when a JDK 8 compatiable proguard-base artifact exists on Maven Central).
- Add Google Guava 17 dependency for various utility, collections, etc. support.
- Add org.json dependency to allow for easy and acceptably efficient JSON code.
- Add annotations to allow code to be explicitly ignored by the animal-sniffer-plugin via a compile-time dependency.
- Add proguard-base-5.0beta2.jar (as well as source and javadoc JARs) to libs directory to implement a hackaround to the unavailability of JDK8 compatiable proguard artifacts on Maven Central.
- Add new gitignore to proguard libs folder to override default project-wide gitignore (we actually want JARs in our source tree for the hackaround).
Add new JSR-305 related annotations.

- Add annotation to annotate all method return values as javax.annotations.Nonnull by default.
- Add annotation to annotate all class field values as javax.annotations.Nonnull by default.
- Add package-level Javadoc file to new annotations.jsr305 package.
Add Dopbox specific OAuth consumer data class.

- Add DropboxAppOAuthData class to handle OAuth consumer (aka Application) data.
- Add package-level Javadoc file to new internal.dropbox package.