(#23) Support for reloading of .jshintrc

The content of .jshintrc for a project is cached. The cache should
be updated when the config file changes.
(#16) Support for custom module paths for jshint/jslint

Alternatively to the bundled jshint.js and jslint.js, the global
`jshint` and `jslint` modules can be defined by setting
`jshint-mode-jshint-path` or `jshint-mode-jshint-path` in emacs
configuration.

Eg: For the global installation of jshint, set
`jshint-mode-jshint-path` to "jshint"

    (setq jshint-mode-jshint-path "jshint")
Merge branch 'reload-jshintrc' into my-master
(#16) Handle globals for jshint config

Newer versions of JSHint handle globals definition separately and
requires them as a extra argument to the hint function.
Merge branch 'configurable-jshint-path' into my-master
Support for custom tempfile creation helpers

Having tempfiles at the same place as the actual file interferes with
the build systems. Eg: grunt/gulp watching on all .js files. Hence, the
copy should be allowed to exit in a different location.

Default behaviour still stays though.

Signed-off-by: Rohan Jain <crodjer@gmail.com>
Merge branch 'custom-tempfiles' into my-master