Remove PBKDF1 implementation for a new branch

Revert "Implement PBKDF1 algorithm"
This reverts commit 8d8da1fd7ddb936822626a3847b393f544d3fb5e.

Revert "Add description for PBKDF1"
This reverts commit a1a0542d20d65c7914c18f8d7170f2843b8174f0.