Added progress bar, fixed documentation issues. Package builds correctly


I added a progress bar to `create_map_df.R` and also `download_kml.R` although the second one gets called from the first and doesn't seem like it needs one.

* I removed empty example blocks from a couple of functions to pass documentation checks
* Added some missing arguments (see [here](https://github.com/ropensci/rWBclimate/blob/progressbar/R/get_ensemble_stats.R#L23))

Package now passes checks. 

To install:

```coffee
install_github("ropensci/rWBclimate", ref = "4e674bb")
```
There are other minor things to resolve in terms of package checks. See:

```
* checking R code for possible problems ... NOTE
climate_map: no visible binding for global variable 'long'
climate_map: no visible binding for global variable 'lat'
climate_map: no visible binding for global variable 'group'
* checking Rd files ... OK
* checking Rd metadata ... OK
* checking Rd cross-references ... OK
* checking for missing documentation entries ... WARNING
Undocumented code objects:
  'Africa_basin' 'Africa_country' 'Asia_basin' 'Asia_country'
  'Eur_basin' 'Eur_country' 'NoAm_basin' 'NoAm_country' 'Oceana_basin'
  'Oceana_country' 'SoAm_basin' 'SoAm_country' 'cb'
Undocumented data sets:
  'Africa_basin' 'Africa_country' 'Asia_basin' 'Asia_country'
  'Eur_basin' 'Eur_country' 'NoAm_basin' 'NoAm_country' 'Oceana_basin'
  'Oceana_country' 'SoAm_basin' 'SoAm_country' 'cb'
All user-level objects in a package should have documentation entries.
See the chapter 'Writing R documentation files' in the 'Writing R
Extensions' manual.
* checking for code/documentation mismatches ... OK
* checking Rd \usage sections ... OK
* checking Rd contents ... OK
* checking for unstated dependencies in examples ... OK
* checking contents of 'data' directory ... OK
* checking data for non-ASCII characters ... WARNING
  Warning: found non-ASCII strings
  '<c3><85>land' in object 'cb'
  'C<c3><b4>te d'Ivoire' in object 'cb'
  'Saint Barth<c3><a9>lemy' in object 'cb'
  '<c3><85>land Islands' in object 'cb'
* checking data for ASCII and uncompressed saves ... OK
* checking installed files from 'inst/doc' ... OK
* checking examples ... OK
* checking PDF version of manual ... OK
WARNING: There were 3 warnings.
NOTE: There were 2 notes.
```

Nothing to worry about but declaring these at the beginning of functions usually helps. Install it and try it out before merging.