geckodriver: Update version number for release

Source-Repo: https://github.com/mozilla/geckodriver
Source-Revision: 11656587d1879ef858e865cb0c770075e1658e6c

--HG--
extra : rebase_source : d5c79b209b478e2c25765eebdd06b20402d8f84a

testing/geckodriver/Cargo.lock

@@ -1,6 +1,6 @@
 [root]
 name = "geckodriver"
-version = "0.14.0"
+version = "0.15.0"
 dependencies = [
  "chrono 0.2.25 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.20.5 (registry+https://github.com/rust-lang/crates.io-index)",

testing/geckodriver/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "geckodriver"
-version = "0.14.0"
+version = "0.15.0"
 authors = [
   "James Graham <james@hoppipolla.co.uk>",
   "Andreas Tolfsen <ato@mozilla.com>",