Tried to address awkward API issue when append query parameters.

[glynos]

Breaking changes in the uri_builder interface.

The report in #61 is correct in that the interface is awkward and confusing. It was also buggy (encoding didn't happen correctly).

I fixed the encoding issue, and explicitly renamed the functions to:

append_query
append_query_key_value_pair

Although this is a bit more verbose, it removes the element of inconsistency. I would be open to renaming these functions, if there are better names.

Finally, to address the commentary in #61:

"I struggle to think of a use case where, when using uri_builder, I would want to undo a previous call to query by replacing its result with a subsequent call to query"

I agree, but in the very unlikely event that someone needs this, they can simply call "clear_query" before starting again.

[deanberris]

Oops, conflicts with other changes -- do you mind updating the branch with either a merge or a rebase?

[glynos]

Fixed the conflicts. Are you OK with the changes?

[deanberris]

LGTM

Yes, this is fine -- thanks @glynos.