v0.5.0

Changelog

6870a6a Add custom useragent to magician
5c19cf2 Add instructions to use go library
2e4834c Clarification for when to fix embedded
eef88e0 [gcp] uncomment sha256 check
113a583 add contributing section to README
f8f2ae3 add fileToTar method
255c178 add guide for adding a new helper
5de39a0 add link to docker cred helper image
d40680a add project history to README
aef2abc add pull request workflow
e389245 allow for custom helpers, mappings dirs
28b9099 clean up mutate, add godoc comments
a5bcf1d cleanup mutate helper methods
f149f1d combine funcs for env vars, split build step
cd113b2 fix bug with etc/, rename util functions
7b85ada fix for bad readme links
9b4633b fix go example formatting
baf2ee7 fix go example formatting (again)
aa41f04 formatting for supported slugs
f7735f3 option to set writer on magician
34025f0 remove bad println
b773b59 udate supported helpers to include slug