webadmin,userportal: Use X-UA-Compatible with IE=10

This patch is meant to address problems when loading
GWT applications in Internet Explorer 11.

IE11 user agent string is missing the "MSIE" part but
instead includes the "like Gecko" part. For example:

  Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko

This causes GWT selector script (*.nocache.js) to pick
and load Firefox (Gecko) permutation of GWT application.

Since IE11 has issues with Gecko permutation [1], the
workaround is to tell IE11 to render page as IE10:

  <meta http-equiv="X-UA-Compatible" content="IE=10">

[1] http://code.google.com/p/google-web-toolkit/issues/detail?id=8228

This shouldn't affect behavior of GWT applications
when loaded in earlier Internet Explorer versions:
- IE8: selector script uses 'ie8' permutation
- IE9: selector script uses 'ie9' permutation
- IE10: selector script uses highest available
  permutation ('ie9')

Note: there might be issues with IE10 + 'ie9' GWT
permutation combination. These issues should be
addressed as part of GWT upgrade which should add
proper support (permutation) for IE10.

Change-Id: Ifad89cbd057fc63944a09478ed92e29c13a49e04
Signed-off-by: Vojtech Szocs <vszocs@redhat.com>