Add option to create indexes in HDFStore if user is using PyTables Pro / PyTables 2.3+

[wesm]

Should just silently fail otherwise if the PyTables version in use does not have the indexing functionality. Should be fairly simple to add, only affects Table formatted objects

[jreback]

requires pytables 2.3.1 at a minimum (the 'pro' version which is now open source)
currently a bug in the indexing routines in pytables that prevents an index on a Time64Col from working - see PyTables/PyTables#119

pandas should try to index the 'index' column in (and only) a table, probably by default
how to deal with a pytables version that is not supported?

[jreback]

this is actually pretty easy since 0.8.1....as now the indicies are Int64 and thus indexing works great
I by default index the 'index' column in all of my panels, but this could be provided as an option....I will take a hack at this after 0.9.1 comes out....

will have to disable auto-indexing for any Time64Cols though....

[jreback]

pytables_docs closes this PR