- client: Add default mode in the DNS settings: Merge pull request #650 in DNS/adguard-home from fix/1770 to master

Close #1770

Squashed commit of the following:

commit c1f75ea643623af78de020bd1bc49aa5b66e25c4
Merge: a5df78ad a869ec4c
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Wed Jun 10 18:56:24 2020 +0300

    Merge branch 'master' into fix/1770

commit a5df78ad303305efcafcfa2a170ff567a3a06db5
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Wed Jun 10 12:50:50 2020 +0300

    Revert "Update locales"

    This reverts commit 4b2b4499dea12949c53bce4ceeed595c17df84c6.

commit 4b2b4499dea12949c53bce4ceeed595c17df84c6
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Tue Jun 9 19:56:34 2020 +0300

    Update locales

commit 790cff0db84b5905362d2e2702b2cbca5c3c90b0
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Fri Jun 5 17:56:01 2020 +0300

    Update Upstream component with new api, extract reduxForm HOC names in constant

commit 72de3d5a92cc33d5b234c837879fc6990291e07b
Merge: 92a4a6ae 501a4e06
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Fri Jun 5 15:55:39 2020 +0300

    Merge remote-tracking branch 'origin/update-dnsproxy' into fix/1770

commit 501a4e06ab350e46ff78656141d925de9f2e4996
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Jun 5 12:47:13 2020 +0300

    openapi

commit 3930bd196572924f164ed011629356a0ac0ec631
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Jun 5 12:21:32 2020 +0300

    * DNS API: new setting "upstream_mode"; remove "fastest_addr", "parallel_requests"

    * use dnsproxy v0.29.0

commit 92a4a6ae24793a2a9ca05ad3ef2078573fd4d059
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Thu Jun 4 18:53:42 2020 +0300

    - client: Add default mode in the DNS settings

client/src/__locales/en.json

@@ -3,6 +3,8 @@
     "example_upstream_reserved": "You can specify DNS upstream <0>for the specific domain(s)</0>",
     "upstream_parallel": "Use parallel requests to speed up resolving by simultaneously querying all upstream servers",
     "parallel_requests": "Parallel requests",
+    "load_balancing": "Load-balancing",
+    "load_balancing_desc": "Query one server at a time. AdGuard Home will use the weighted random algorithm to pick the server so that the fastest server will be used more often.",
     "bootstrap_dns": "Bootstrap DNS servers",
     "bootstrap_dns_desc": "Bootstrap DNS servers are used to resolve IP addresses of the DoH/DoT resolvers you specify as upstreams.",
     "check_dhcp_servers": "Check for DHCP servers",