Replace 'yauaa' with a less-costly user agent parser

We currently use the Yauaa library for parsing user agent strings to determine whether the user's browser is compatible with our product. This library turns out to be overkill, since it uses a costly in-memory cache of a large number of possible input strings for speed-optimized recognition, intended for high-volume log processing. We only need a lightweight recognition of "chrome or not" in the browser. The hundreds-of-MB memory cost is not justified for this use case.