examples/gowiki: Added error handing for saveHandler function.
examples/gowiki: Added template caching functionality.

Modified renderTemplate() and added global variable "templates".
examples/gowiki: Added validation to path.

Created a regexp.Regexp variable as a global variable and
created a function to utilize it, called getTitle(). Then,
the handler functions were refactored to use this function
to retrieve the titles for their respective pages.