Add "chaise" namespace to all the special classes and attributes

[RFSH]

As part of #958, I've added a new attribute, which brought up a discussion about attributes and class names. Given that we want to avoid collision of our special attribute/class names with outside ones, we decided to always add the chaise namespace. We thought the distinction between ermrestjs and chaise doesn't matter in this case, and we just want a namespace that signals it as our internal tool.

The following is the list of class names and their new names:

Current name	New name	Notes
.chaise-btn	No change
.download-alt	.chaise-download	Chaise download button. Chaise also shows the same style with just `download` attribute.
.download	should we remove it?	Alternative for .chaise-btn .chaise-btn-primary (Kept for backwards compatibility)
.vocab	.chaise-vocab
.chaise-autofill	No change
.fullscreen-off	.chaise-iframe-fullscreen-btn-off
.chaise-image-preview	No change
.chaise-color-preview	No change
.asset-permission	.chaise-asset-permission
.external-link	.chaise-external-link
.external-link-icon	.chaise-external-link-icon
.external-link-no-icon	.chaise-external-link-no-icon
.hide-in-print	.chaise-hide-in-print
.video-info-in-print	.chaise-show-in-print	Added by ermrestjs to video description, but there's no reason to be use a name this specific.

While discussing this change, we also talked about backward compatibility.

• We decided that our first change should still keep the old names, and we should offer ways to facilitate the migration process.
• We should develop a programmatic way (a regular expression that can be used in an ermrest query or a script) to find whether these old class names are used in the database.
• Another suggestion was to introduce a flag so they can switch between the old and new ones (not sure how helpful this might be and requires more thinking).