Add Override Annotations Across Project

Adding remaining override annotations across mybatis.
Update clirr version to last released

Update the CLIRR comparison version to 3.2.7 which was last released and
ordered in properties section alphabetically.
Removed excess spacing

Removed some spacing that was on empty lines or trailing end of lines.
Fix some autoboxing

Try not to allow use of auto boxing as it is unclear.
Smart 'if' statement

Use smart 'if' statement on returns where check was for null and
returning null otherwise value.  This does fix one return per method in
some cases per sonar.
Replace ArrayList Creation on a return

Array list was being returned using non standard way of creating the
array as essentially an internal class.  No real good reason for this
and it was being flagged via sonar for not exposing private constructor
to prevent synthetic access.  Much cleaner approach is to just build the
array without the internal class.
Fix possible null pointer exception

Fix possible null pointer exception where developer was trying to
outsmart the null pointer checks by using a flag for null pointer.  This
caused eclipse to see a potential null pointer even though there was not
one.  Since the check was only used once, just inlined it.
Remove Unthrown Exceptions

Removed some exceptions that were not actually thrown.
Remove unnecessary 'else' statements

When 'return' occurs in 'if' statement, there is no reason to have an
else statement.  While this is in quite a few places, just cleaned up a
couple of them.  One for clarity and the other to move a line ending
comment that sonar complained about.
Synthetic Access

Add public constructors so synthetic access is not used per sonar.  Also
fix accessors.
Add private constructors to static classes

Private constructors needed in static final classes to prevent
instantiation of the class.
Fixed some types on maps & various other objects.
Remove redundant thrown exception

Unchecked BindingException, don't throw it, that is redundant.
Revert jdk7 override

Two overrides turned out to be jdk7 only.  Comment them out and add note
regarding this.  Also fixed trailing comment.
Java Compliance Order

Move object to correct location in class.
Prevent Instantiation

Prevent instantiation using private constructor in static classes.
Byte Array Util cleanup

Prevent instantiation of static class.
Avoid autoboxing and unnecessary object creation.
Removed unnecessary override

Override that only calls super method is not necessary as it inherits
super class.
Do not create extra objects that are returned

Do not create objects and immediately return them.  Just return
directly.
NodeHandler internal class cleanup

Change NodeHandler to not be an internal class creating itself but
rather a method in default scope.  Have it perform the get and simply
return the NodeHandler as that is the only usage.
Change README to markdown and update

Changed to markdown.
Added badges for travis CI and maven central.
Added mybatis logo.