Normalize recipe instructions, yield, and image url

Including tests and example recipe data.

requirements.dev.txt

@@ -5,6 +5,7 @@ APScheduler==3.6.3
 astroid==2.4.2
 async-exit-stack==1.0.1
 async-generator==1.10
+attrs==20.3.0
 beautifulsoup4==4.9.1
 black==20.8b1
 certifi==2020.6.20
@@ -24,6 +25,7 @@ html-text==0.5.2
 html5lib==1.1
 httptools==0.1.1
 idna==2.10
+iniconfig==1.1.1
 isodate==0.6.0
 isort==5.4.2
 itsdangerous==1.1.0
@@ -36,12 +38,16 @@ mccabe==0.6.1
 mf2py==1.1.2
 mongoengine==0.21.0
 mypy-extensions==0.4.3
+packaging==20.8
 pathspec==0.8.0
+pluggy==0.13.1
 promise==2.3
+py==1.10.0
 pydantic==1.6.1
 pylint==2.6.0
 pymongo==3.11.1
 pyparsing==2.4.7
+pytest==6.2.1
 python-dateutil==2.8.1
 python-dotenv==0.15.0
 python-multipart==0.0.5
@@ -50,7 +56,7 @@ pytz==2020.4
 PyYAML==5.3.1
 rdflib==4.2.2
 rdflib-jsonld==0.5.0
-regex==2020.7.14
+regex==2020.11.13
 requests==2.24.0
 Rx==1.6.1
 scrape-schema-recipe==0.1.1