This suggestion pops up once in a while, so there are many users stumbling about this. These services used to be included in std_srvs once upon a time but were intentionally removed in 2012:
Ken Conley wrote back then:
one of the reasons we purged so many services is that its
hard to have semantically meaningful common services. Services are
more equivalent to method declarations, so a ‘GetBool’ service is
similar to naming a method or interface, ‘GetBool’. There are cases
where such a method is reasonable, but it doesn’t provide any higher
level semantic other than the type signature.
http://lists.ros.org/lurker/message/20120201.115037.1eb65481.en.html