Renaming mesh files for a better convention

rtb-data/rtbdata/meshes/Lynxmotion/AL5D/base.stl

rtb-data/rtbdata/meshes/Lynxmotion/AL5D/elbow.stl

rtb-data/rtbdata/meshes/Lynxmotion/AL5D/gripper.stl

rtb-data/rtbdata/meshes/Lynxmotion/AL5D/link3.stl

rtb-data/rtbdata/meshes/Lynxmotion/AL5D/link4.stl

rtb-data/rtbdata/meshes/Lynxmotion/AL5D/shoulder.stl

rtb-data/rtbdata/meshes/Lynxmotion/AL5D/waist.stl

rtb-data/rtbdata/xacro/al5d_description/meshes/base.stl

rtb-data/rtbdata/xacro/al5d_description/meshes/elbow.stl

rtb-data/rtbdata/xacro/al5d_description/meshes/gripper.stl

rtb-data/rtbdata/xacro/al5d_description/meshes/link3.stl

rtb-data/rtbdata/xacro/al5d_description/meshes/link4.stl

rtb-data/rtbdata/xacro/al5d_description/meshes/shoulder.stl

rtb-data/rtbdata/xacro/al5d_description/meshes/waist.stl