ETag handling is broken / always return `undefined`

[olessavluk]

Hello!

In file https://github.com/comapi/comapi-sdk-js/blob/master/src/profile.ts#L126 you often get etag using following code:

this._localStorage.setString("MyProfileETag", Utils.getHeaderValue(result.headers, "ETag"));

// where this util method implemented like:
public static getHeaderValue(headers: Object, key: string) {
    return headers[key] || headers[key.toLowerCase()];
}

Here you are trying to get it by keys ETag or etag, but both of those fail because you server return it as Etag(see small t):

Because of this ETag value always undefined and depending on localStorageData implementation fails during request (or just always ignored)

[Univibe69]

I have modified getHeaderValue() to be able to deal with this. It looks like the case of the header names varies depending on the HTTP client you are using. Hopefully will be releasing a new version next week