refactor(url_template): simplify the parameter regexp

as "\w" already includes "0-9"
refactor(regexp): simplify regexps

Most chars do not need escaping in classes
refactor(route): created Route interface to get rid of dart2js warnings

Fixes #11
chore(release): 0.4.15
chore(karma): update karma version
Merge pull request #23 from vicb/patch-1

refactor(url_template): simplify the parameter regexp
Merge pull request #24 from vicb/regexp

refactor(regexp): simplify regexps
style: code cleanup
feat(router): allow not leaving when only params change

Fixes #1
chore(router): minor cleanup around dontLeaveOnParamChanges