gtrendsR 2.0.0 (unreleased)

Major change

Due to recent changes to Google Trends API, gtrendsR has been almost re-written form scratch. One big visible change is that signing into a Google account is no longer required to download data from Google Trends.
Added a vignette (TODO)

Added some missing country codes (#94). data("countries").
Now able to specify for which Google products the request is performed using the gprop parameter (#112). Possible values are froogle for Google shopping, new for Google news, youtube for Youtube videos and images for Google images.
Now able to query using Google categories ?gtrends (#89).
Returned data is now tidy (#110). The trend object now contains keyword, hits and location header (head(sport_trend$trend)).
Fixing a bug where overriding countries variable was breaking package's functionalities (#109).
Correct default fallback for querying for google.user and google.password in gconnect (#121)

Fixing login issue due to backend changes made by Google (#103). Thanks to @MrLoh for initial implementation and suggestions.
Fixing crash occuring when monthly data was returned (#81).
gtrends() will throw a warning if data is returned monthly (#80).
gtrends() is now correctly detecting when quota limit is reached (#90).

A ggplot2 object can now be returned for further customization. plot(gtrends("NHL")) + ggtitle("NHL trend") + theme(legend.position="none")
Support for hourly and daily data (#67). For example, it is now possible to have hourly data for the last seven days with gtrends("nhl", geo = "CA", res = "7d"). Use ?gtrends for more information about the time resolution supported by the package.
Support for categorties (#46). Ex.: gtrends("NHL", geo = "US", cat = "0-20") will search only in the sport category.
Some countries (ex: Hong Kong) were missing from the list (#69).
Various typos and documentation work.

Added support for sub-countries (#25). Ex.: gtrends("NHL", geo = "CA-QC") will return trends data for Québec province in Canada. The list of supported sub-countries can be obtained via data(countries).
Data parsing should work for any data returned by Google Trends (i.e. countries independent).
Better support for queries using keywords in different languages (#50, #57). Ex.: gtrends("蘋果", geo = "TW")
Now able to specify up to five countries (#53) via gtrends("NHL", geo = c("CA", "US"))
Fixing issue #51 allowing UK-based queries via geo = "GB"

Fixing issue #34 where connection verification was not done properly.
Now able to use more latin character in query. For example: gtrends("montréal").
Can now deal with data returned other than in English language.