Fix ltc_scrypt dependency for RPC tests

- travis: RUN_TESTS requires python3-dev. This enables us to
  compile the ltc_scrypt library under python3
- pull tester deps: use curl instead of wget to reduce dependencies
  as everything else uses curl

.travis.yml

@@ -43,6 +43,7 @@ install:
     - if [ -n "$DPKG_ADD_ARCH" ]; then sudo dpkg --add-architecture "$DPKG_ADD_ARCH" ; fi
     - if [ -n "$PACKAGES" ]; then travis_retry sudo apt-get update; fi
     - if [ -n "$PACKAGES" ]; then travis_retry sudo apt-get install --no-install-recommends --no-upgrade -qq $PACKAGES; fi
+    - if [ "$RUN_TESTS" = "true" ]; then travis_retry sudo apt-get install --no-install-recommends --no-upgrade -qq python3-dev; fi
 before_script:
     - unset CC; unset CXX
     - if [ "$CHECK_DOC" = 1 ]; then contrib/devtools/check-doc.py; fi

qa/pull-tester/install-deps.sh

@@ -2,7 +2,7 @@
 
 # installs test dependencies
 
-wget https://github.com/langerhans/ltc-scrypt/archive/master.tar.gz
+curl -L https://github.com/langerhans/ltc-scrypt/archive/master.tar.gz --output master.tar.gz
 echo "ade3cdf498927990b6d153d74f0da104114e838584be5a81bef8972accd03341 master.tar.gz" | sha256sum -c
 tar zxf master.tar.gz
 pushd ltc-scrypt-master