bump to support v8go v0.7.0

• #3 upgrade for v8go v0.7.0 (@danielgatis)

v0.4.0

• all: set inject attribute to readonly

• timers: use time ticker to replace sleep

• v8go: bump to v0.6.0

v0.3.2

• console: fix console.log not work

v0.3.0

• timers: add setTimeout, clearTimeout, setInterval and clearInterval support

v0.2.0

• fetch: add response headers get and has function support