Began adding support for file ranges.  Added two methods:
get_patent_webpage returns the html data for a given URL, and extract_filenames_from_webpage takes html data and extracts the file locations of all the links with href attributes matching the regular expression ```i?p(?:a|g)\d{6}.zip```.  This code is very basic and is not integrated into the rest of the code at all right now.  However, the output can be seen with the command ```p extract_filenames_from_webpage get_patent_webpage "http://patents.reedtech.com/parbft.php"```.
Added (somewhat rudimentary) support for file ranges.  Users can pass single files exactly as before, but they can also now pass ranges of filenames. For example: ipg111127-ipa121204.zip gets all the patent grants between those dates.  This example also illustrates some of the shortcomings with the current implementation.  ipg111127.zip is not actually a file, which is fine behaviorally, but may confuse users.  Additionally, the prefix of the second filename does not matter.  It is stripped out and ignored.  However, some sort of warning should be put in place if the user attempts to pass a range with different patent types.
Changed auto_extract_filenames_... to use a map function instead of an empty array and an each function.  Removed webpage parse support for filenames which did not start with an i (pa... or pg...)
Working Commit - Does not run past the first exit keyword.
Added support for more range formats, switched file ranges into a separate struct object, added a class called FileArgumentsParser to handle parsing of file arguments.  Essential functionality not implemented: type is only set for the filename format, as there is not implementation for parsing patent type keywords yet.  The program does not run past the exit statement because there is not yet implementation for checking what types of ranges are present.
Finished adding support for mm/dd/yy formatted ranges, ptype keywords preceding the ranges, and various other functionalities.  The ranges can be given as [ipa|ipg|both] mm/dd/yy-mm/dd/yy, [ipa|ipg|both] yymmdd-yymmdd, or [keyword ommitted] [ipa|ipg]yymmdd-yymmdd (this may change).
merged Alex's date range changes
Merge pull request #16 from kevinburleigh75/master

Adds date range processing