make conversion to path enabled sequnece file easy

[vadasg]

Generating a SequenceFile with g._() is often the first step if you are going to do repeated analyses. However, this does not generate a path enabled SequenceFile by default.

It would be nice if there were an easy way to enable paths for queries that start with this SequenceFile, or to enable paths on the file after it is generated.

According to Marko: there is no "semantically easy way" to make an already generated SequenceFile into a path enabled SequenceFile. You will have to stream one off of HBase. E.g. g.enablePath()._() -> github-withpaths.

[okram]

We might want to create a new type of SequenceFile extension called RawGraphSequenceFile that will write the output to that and as such, all enabled paths are set to false. .......................... or we have a helper utility like this: FaunusUtility.enablePath(seqFileLocation, boolean).

easy to do either, just need to think of best way to do it.

[okram]

We should really make path enabling transparent to users... this is one of the most awkward "features" in all of Faunus.. This needs good thought.