update metadata import

- Fixing bug in test scripts introduced by
  `RCurl::url.exists()`. Regular words do suddenly return `TRUE`. WTF?
  But entering a invalid URL does still result in `FALSE`.
- The `extract.station.name.and.location` function is now obsolete and
  the `extract.content.climate` function handles the import of the
  metadata using the `import.file.metadata.climate` function for now.
  Since the DWD decided to not keep the description files up to date
  anymore, some stations are not mentioned in there and can not be
  handled afterwards. Therefore I now directly obtain the metadata
  from the *Metadaten_Geographie_* files.
- The encoding was fixed. *latin1* is used instead of *UTF-8* and
  handed over via the *fileEncoding* and not the *encoding* argument
  in `read.table`.

update to version 0.1.1
- Fixing namespacing in the example of `get.dwd.ftp.url()`.
- Explicitly use `stats` namespace for `rnorm` function in
  `dwd2r.url.check()`
- Adding the **dwd2r.md** vignette taken from the corresponding blog
  post.
- A bug in the `readline()` function causes it to only read multiple
  characters if there is no trailing whitespace. There was, however,
  one present in each call and thus all choices larger than 9 could
  not be accessed

initial release of the dwd2r package