Bump asm version to 5.0.3

5.x release added support for Java 8 and fixed some bugs: [1].

[1] http://forge.ow2.org/forum/forum.php?forum_id=2302

Change-Id: If5009c676e76bfd420d71a710157e57be0c1511a
Update GWT to 2.7

As pointed out in this thread on GWT-discuss development group [1],
gwt-dev is going to be unbundled in 2.7 release. That means that we
would have to supply its dependencies explicitly.  To start with we
need to pass in ASM library.

It's unclear though, if we need asm-commons and asm-xml as it compiles
without it, but corresponding parent-pom contains it [2].

GWT unit tests were disabled as gwt-test-utils doesn't seem to work yet
against upcoming GWT 2.7 release. Issue was filed upstream [3].

As was pointed out in this thread [4], codeserver is now shipped in
gwt-dev.jar as well. Stop fetching codeserver.jar in addition and use
the bits from gwt-dev.jar.

[1] https://groups.google.com/d/topic/google-web-toolkit/LwXXQCG_I_k/discussion
[2] http://repo1.maven.org/maven2/org/ow2/asm/asm-parent/5.0.3/asm-parent-5.0.3.pom
[3] https://github.com/gwt-test-utils/gwt-test-utils/issues/68
[4] https://groups.google.com/d/topic/google-web-toolkit-contributors/pFYPE7Uoub8/discussion

Bug: issue 3008
Bug: issue 3027
Change-Id: Ib8f9ed0c767e9f41f104253fdc8b74a8cbbe38ab
Improve GWT SDM debug session recompilation time by a factor of 10

One of the major features of upcoming GWT release 2.7 is incremental
compilation in SDM session.  Because Buck recompilation is
integrated as HTTP filter on every request, this optimization is
jeopardized: Buck is unaware that a SDM debug session is active.
We cannot entirely skip the Buck integration in SDM debug session
as the site must be initialized at least once.

Pass a Java property from Eclipse launch configuration and maintain
initialization map with initialized flag per user agent for the site.
This improves the time by a factor of 10, ca. 2 sec. for incremental
recompilation on my laptop:

   Compilation succeeded -- 1,822s
   Linking into
   <site>/gerrit-gwtui/com.google.gerrit.GerritGwtUI/compile-5/war/gerrit_ui;
   Writing extras to
   <site>/gerrit-gwtui/com.google.gerrit.GerritGwtUI/compile-5/extras/gerrit_ui
   Link succeeded
   Linking succeeded -- 0,190s
   2,140s total -- Compile completed

Change-Id: Id2cb19a675d500c04e6748216a77dbb4f26fa1ab