Home housekeeping and minor refactoring cleanup.

Changed README from AsciiDoc (.asciidoc) to traditional markdown (.md).
Plan to use AsciiDoc for more in depth documentation guides, but stick
to more general markdown for README files.

Renamed 'ScalaFileImporter' to (the more appropriate) 'DefaultFileImporter'.

Renamed 'FileImporter' and 'DirectoryImporter' to 'FileBundleImporter' and
'DirectoryBundleImporter' respectively.

Fixed indefinite directory recursion.

Shortened 'Bundle' property "bundleSymbolicName" to "bsn" to make
queries easier on the fingers.
Add new "UsesConstraint" entity.

The "UsesConstraint" connects an exported package to
the bundle declaring a "uses" constraint for that exported package.
This gives us the ability, in the case of multiple package providers,
to track back to which specific bundle is declaring a uses constraint
for the exported package.

Here's a cypher query to run against these new relationships:
MATCH (b)-[:EXPORTS]->(p)<-[:PACKAGE]-(uc:UsesConstraint)-[:USES]->(used)
RETURN b,p,uc,used LIMIT 10;
Added drone.io build badge to README.
Merging updates from master.
Accept args from command line.

You can now pass the following arguments:
args[0] - The directory to scan (required).
args[1] - Whether to scan recursively, either 'true' or 'false (default is false).