Fix typos and cache is crs-aware

[dieghernan]

Following #189 and #190

• Fix typo: dieghernan@5c7e205
• Move comparison to string\string instead of string\integer (now it is year == "2016"). Although string\integer worked it seems just right to perform the comparison between the same data types: dieghernan@f93714b
• Update for caching, so now it is crs-aware. I didn't spotted this one, meaning that get_eurostat_geospatial(year =2013, crs=4326) and get_eurostat_geospatial(year = 2013, crs=3857) produced the same result (since 4326 was cached in first place and 3857was updated from cache). Potential workaround is to set update_cache = FALSE).

[dieghernan]

Close since I added extra files