fix typo in 'Elliptic-1', 'Slit-1', 'Slit-2'

RegressionTests/Elliptic-1/Elliptic-1.local

 #!/bin/bash
-timeout 300 mpirun -np 2 "$OPAL_EXE_PATH/opal" "$@" elliptic-1.in --info 3 --warn 0 2>&1 
+timeout 300 mpirun -np 2 "$OPAL_EXE_PATH/opal" "$@" Elliptic-1.in --info 3 --warn 0 2>&1 

RegressionTests/Slit-1/Slit-1.local

 #!/bin/bash
-timeout 300 mpirun -np 2 "$OPAL_EXE_PATH/opal" "$@" slit-1.in --info 3 --warn 0 2>&1 
+timeout 300 mpirun -np 2 "$OPAL_EXE_PATH/opal" "$@" Slit-1.in --info 3 --warn 0 2>&1 

RegressionTests/Slit-2/Slit-2.local

 #!/bin/bash
-timeout 300 mpirun -np 2 "$OPAL_EXE_PATH/opal" "$@" slit-2.in --info 3 --warn 0 2>&1 
+timeout 300 mpirun -np 2 "$OPAL_EXE_PATH/opal" "$@" Slit-2.in --info 3 --warn 0 2>&1