ensure getRawQuery is not null before appending

Motivation:

without this check then given a URI with path /path the resulting URL will be /path?null=

Modifications:

check that getRawQuery doesn't return null and only append if not

Result:

urls of the form /path will not have a null?= appended
Motivation: Sonar points out an equals comparison, where the types compared are different and don't share any common parent http://clinker.netty.io/sonar/drilldown/issues/io.netty:netty-parent:master?severity=CRITICAL#

Modifications:
Converted AsciiString into a String by calling toString() method before comparing with equals(). Also added a unit-test to show that it works.

Result:
Major violation is gone. Code is correct.
Compress the heap dump after tests are finished

Motivation:

Tests sometimes time out because it took too long to compress the
generated heap dump.

Modifications:

- Move the compression logic to a new method 'compressHeapDumps()'
- Call TestUtils.compressHeapDumps() at the end of the tests, so that
  the tests do not fail because of timeout

Result:

JUnit reports the real cause of the test failure instead of timeout
exception.
Log detailed information about renegotiation and traffic

Motivation:

We need more information to understand why SocketSslEchoTest fails
sporadically in the CI machine.

Modifications:

- Refactor SocketSslEchoTest so that it is easier to retrieve the
  information about renegotiation and the current progress

Result:

We will get more information when the test fails.
Fix checkstyle
Java ALPN provider version update

Motivation:

There was a bug in the Java ALPN library we are using.  A new version was released to fix this bug and we should update our pom.xml to use the new version.

Modifications:

Update pom.xml to use new ALPN library.

Result:

Newer versions of JDK (1.7_u71, 1.7_u72, 1.8_u25) have the bug fixed.
Do not use SLF4J/Logback API directly

Motivation:

TrafficShapingHandlerTest uses Logback API directly, which is
discouraged.  Also, it overrides the global default log level, which
silences the DEBUG messages from other tests.

Modifications:

Remove the direct use of Logback API

Result:

The tests executed after TrafficShapingHandlerTest logs their DEBUG
messages correctly.