Switch icu repo to icu.git from icu52.git

Switch icu repo to icu.git from icu52.git

We're switching from svn to git for icu and dropping the icu major
version number from the repo name.

Besides, roll ICU to 53ecf0f68b27a004bef5526553b8e5f6c235b80b (adding
codereview.settings ; https://codereview.chromium.org/775153003/

BUG=438401
TEST=gclient sync succeeds and third_party/icu comes from icu.git
instead of icu52.git
TBR=vadimsh@chromium.org

Committed: https://crrev.com/b0a58a7eb0001b434824c7d7dbf49a85cbb17561
Cr-Commit-Position: refs/heads/master@{#306910}

[jungshik at Google, 2014-12-04 00:42:19]

jshin@chromium.org changed reviewers:
+ vadimsh@chromium.org

[jungshik at Google, 2014-12-04 00:43:25]

The CQ bit was checked by jshin@chromium.org

[commit-bot: I haz the power, 2014-12-04 00:44:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/769413004/20001

[Vadim Sh., 2014-12-04 00:44:51]

lgtm

[commit-bot: I haz the power, 2014-12-04 01:10:53]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-12-04 01:10:53]

Try jobs failed on following builders:
  linux_chromium_gn_dbg on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)
  mac_chromium_rel_ng on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[jungshik at Google, 2014-12-04 20:58:29]

The CQ bit was checked by jshin@chromium.org

[commit-bot: I haz the power, 2014-12-04 20:58:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/769413004/40001

[commit-bot: I haz the power, 2014-12-04 22:26:47]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2014-12-04 22:27:38]

Patchset 3 (id:??) landed as
https://crrev.com/b0a58a7eb0001b434824c7d7dbf49a85cbb17561
Cr-Commit-Position: refs/heads/master@{#306910}