Resolve SNAPSHOT artifacts with multiple platform nar

Use getBaseVersion() instead of getVersion() when constructing file
paths for lib and include directories for nar dependencies in the
AbstractDependencyMojo.java. This change is same as #79 which probably
missing the AbstractDependencyMojo.java.

Without this change build will be failed if there have multiple nar in
the repositories.  For example:

hw-1.0-20140117.030545-15-x86-Windows-gpp-shared.nar
hw-1.0-20140117.093209-16-amd64-Linux-gpp-shared.nar

The Linux nar is built after the Windows nar. When building the windows
nar, maven will resolve the dependency base on the later timestamp which
will result in resolve failure. Using getBaseVersion will fix this
problem.

This fixes issue #80.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Fix NarTestCompileMojo resolve dependencies SNAPSHOT artifacts

In NarTestCompileMojo after resolving dependencies in
downloadAttachedNars, the SNAPSHOT dependencies will unpack using full
version names instead of SNAPSHOT version name (e.g.
hw-1.0-20140117.030545-15-x86-Windows-gpp-shared.nar). This causes the
testCompile to fail if has SNAPSHOT dependencies.

The change is a workaround to explicitly unpack the NarArtifacts. This
will unpack SNAPSHOT artifacts with expected version names.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a test to verify that SNAPSHOT dependencies are resolved correctly

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'baseversion'

In this topic, the problem is addressed when the NAR plugin would unpack
SNAPSHOT dependencies with an explicit timestamp in their file names,
breaking the linkage.

This closes the pull request #94.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>