Added empty relativePath element to parent in pox.xml in order to avoid Maven warning

[krichter722]

Added empty relativePath element to parent in pox.xml in order to avoid Maven warning.

This avoids warnings in the form of

Some problems were encountered while building the effective model for org.apache.commons:commons-math4:jar:4.0-SNAPSHOT
'parent.relativePath' of POM org.apache.commons:commons-math4:4.0-SNAPSHOT ([path to]/commons-math/pom.xml) points at [aggregator] instead of org.apache.commons:commons-parent, please verify your project structure @ line 19, column 11

It is highly recommended to fix these problems because they threaten the stability of your build.

For this reason, future Maven versions might no longer support building such malformed projects.

if the project is used in an aggregator Maven project and has no downside.

[coveralls]

Coverage decreased (-0.006%) to 90.556% when pulling 3fe0e5cf119b4db2f9ee298e6c05cce64a0550d4 on krichter722:relative_path into 97191fc73cda17794ac44cf2fcae629695001999 on apache:master.

[krichter722]

Closing due to age