e.g:
params: array()
template: /path{?params*}
previous result: /path?params=
correct result: /path
Unfortunately PHP is unable to distinguish between an empty list array
and an empty associative array. However this doesn't matter, because the
empty case of either of these is considered "undefined" by the spec.
http://tools.ietf.org/html/draft-gregorio-uritemplate-08#section-2.3
A variable defined as a list value is considered undefined if the
list contains zero members. A variable defined as an associative
array of (name, value) pairs is considered undefined if the array
contains zero members or if all member names in the array are
associated with undefined values.
http://tools.ietf.org/html/draft-gregorio-uritemplate-08#section-3.2.1
A variable that is undefined (Section 2.3) has no value and is
ignored by the expansion process. If all of the variables in an
expression are undefined, then the expression's expansion is the
empty string.
