openssl and httr should be imported, not suggested

[michbur]

No description provided.

[TymekDev]

Idea behind putting openssl and httr in "Suggests" was taken from httr. httr package has httpuv package in "Suggests", yet it is required to perform the OAuth authorization. Similarly we wanted to limit httr and openssl requirement only to the services that actually require OAuth.

I can see how this change could improve the package's integrity by providing access to every service without installing additional packages (httr and openssl). However, this change would come at cost of higher requirements for every non-OAuth service and would render using plain curl useless, thus preferably requiring a code refactoring to use httr for performing requests.