The Sacramento Area League of Associated Muslims Center, an Islamic center located off Community Oak Drive, will finalize phase three of their mission in May with the completion of their mosque.   Salam Center was established in 1987 in hopes of one day having a complete Muslim community center that would include a library, bookstore, school, counseling center, youth center, family corner and a mosque.   Phase one, which was started in the late 1980s, included on-site work such as boundary walls, landscaping and the front gate.  Phase two, which began in the early '90s, brought the completion of the community center, full-time school, weekend school and kitchen.  Phase three has been d