initial commit. the very basics of the krugmans-blog spider are implementeted by using spider that inherited from scrapy.spider.Spider. im currently not sure if a CrawlSpider would be more convenient.
the crawler now can follow links and extract headline, text and links
scrapy-item extended

the scrapy-item has been extened to store the blogs name, url, release- and crawldate of an entry, author, headline, textbody
and the links metioned in the blog entry.
blogentries are now stored in a local elasticsearch instance. in addition some features have
been added and bugs have been eliminated, respectively:
   * the scrapy-internal logging-mechanism is now in use.
   * linked text is now a part of blogentries body (<a href"..">THIS TEXT</a>)
   * the linkextraction was recreated due to a lack of collecting links to
     pdf-files.
multiple spiders crawl sequentially

this feature is provided by the custom command 'scrapy crawlall'. it executes all
within the project sequentially.
multiple spiders crawl sequentially

this feature is provided by the custom command 'scrapy crawlall'. it executes all
within the project sequentially.
resolved stupid mergeconflict
enhanced core functions

it's now prevented that entries with the same url (i.e. duplicates [hopefully])
are droped to the elasticsearch-instance.
furthermore the krugman-spider has been altered to use the recently discovered
hidden json-interface (which can be found here: http://krugman.blogs.nytimes.com/\
more_posts_json/page/2/?homepage=1&apagenum=1). this enabeles the spider to
crawl aged blogposts.
tapping the archives now.

due to a lack of beeing able to crawl the past, the spiders have been altered
to use the json-based archive-interfaces. this is true for the so far proccessed
blogs: krugman and upshot.
this commit includes a bunch of enhancements including new features

* the blog voxeu.org gets scraped now
* the blog-item-datastructure has been extended with the items:
   * references
   * comments
   * tags
   * teaser
* all spiders are now able to scrape the blog's archive
* spiderparameters have been introduced to limit the scraped items by date
   * the parameters are startDate and endDate
   * invocation example: scrapy crawl krugman.blogs.nytimes.com -a startDate=2014-04 -a endDate=2014-04
* a standard date/time-format has been introduced. example: 2014-04-29T12:45:45
marginalrevolution.com has been added to crawled blogs.
added spider for brad delong's blog
new blogs added:
   Marginal Revolution
   Zero Hedge
Blogs added:
   Econbrowser
   Naked Capitalism
   The Big Picture
some minor changes
Repository clearance

Some files, unnecessary for the project, have been removed.
Merge remote-tracking branch 'github/master'