Honor LD_LIBRARY_PATH settings in start scripts

The start scripts export the LD_LIBRARY_PATH environment variable to "$ERTS_DIR/lib". They should honor existing LD_LIBRARY_PATH required e.g. for running ports.
Merge pull request #135 from hirschenberger/master

Start scripts should honor existing LD_LIBRARY_PATH settings
load scripts from files and templates
add templates
add files
set doc_root on dtl templates
add rebar_vsn_plugin directory to rebar.config
just compile regular files as template modules
fix typo in rel_name tag
assume templates are already compiled, use dtl for files too
unescape quotes
try adding some verbosity to erlydtl compilation errors
exclude dtl scripts from cover
honor existing LD_LIBRARY_PATH in script templates
ignore compiled templates