Changed charset attribute value to double quotes

For formatting consistency
add support for setting custom modifiers in the options

commands can now be functions as well as strings, like so:

	new Medium({
            element: document.querySelector('article.content section.editable'),
            autofocus: true,
            placeholder: 'Write some text.'
            modifiers: {
                188: function() { /* do something here */ }
            }
        })

(cherry picked from commit 2f38e361fe1d7f01845097909b0b5cc1e2fa3464)
Resolving copy-paste issue for Firefox browser
Fixed Issue #51
update index.html to work on either http or https
Merge remote-tracking branch 'origin/pull-2f38e3' into upstream-master

Conflicts:
	medium.js
Merge branch 'upstream-master' into pull-2f38e3
placeholder setClean function
Merge pull request #38 from Hubenet/formatting-consitency

Changed charset attribute value to double quotes
Merge pull request #40 from aggieben/pull-2f38e3

add support for setting custom modifiers in the options
Merge pull request #48 from shilpan/master

Resolving copy-paste issue for Firefox browser
Merge pull request #56 from mikey0000/patch-1

update index.html to work on either http or https
Merge pull request #58 from ncthis/master

Placeholder setClean function
added val an clear methods
Merge pull request #59 from darcyadams/value_clear_methods

Added val and clear methods
Remove trailing commas
Merge pull request #53 from phpmycoder/fix_maxlength_cancels_all_keydowns

Fixed Issue #51 - Full Editor Prevents All Keystrokes
Merge branch 'master' of https://github.com/jakiestfu/Medium.js