invalid index.d.ts for typescript typings

[28harishkumar]

Typings for interface IOptions is wrong in following line.

It must be

    supportsVideo?: boolean,
    maximumCallGroups?: string,
    maximumCallsPerCallGroup?: string,

false, '1' and '1' are values not types. Also according to setup these fields are options.

Seems like this minor update has not tested for typescript.

[danjenkins]

Hey @28harishkumar - thanks for this but theres already another issue for this over at #121

Maybe you could do a Pull Request to fix it?