elastic v0.7.2

MINOR IMPROVEMENTS

• Changed docs_bulk() to always return a list, whether it's given a file,
  data.frame, or list. For a file, a named list is returned, while for a
  data.frame or list an unnamed list is returned as many chunks can be processed
  and we don't attempt to wrangle the list output. Inputs of data.frame and list
  used to return NULL as we didn't return anything from the internal for loop.
  You can wrap docs_bulk in invisible() if you don't want the list printed
  (#142)

BUG FIXES

• Fixed bug in docs_bulk() and msearch() in which base URL construction
  was not done correctly (#141) thanks @steeled !